The Sengoku period (1493-1590) represented a time of turbulent change in Japan.  The period arose out of a gradual loss of control by the central authorities in Kyōto and ended with the unification of Japan under Toyotomi Hideyoshi.  Its defining characteristics included a breakdown of the Ashikaga family and the traditional system of governance known as the Muromachi bakufu,  a transfer of political and military power from the central authorities in Kyōto to the provinces, the rise of provincial warlords who operated outside the control of the bakufu, frequent and extensive conflict within and across provinces, rapidly shifting alliances as daimyō and their clans maneuvered for advantage over their enemies, the phenomenon of gekokujō by which persons of lesser authority usurped their superiors, and a loss influence by the Imperial Court.

The origins of the period

The Sengoku period can be understood in the context of the Muromachi period, which ran from 1336 to 1573.  The Muromachi period was defined by the governance of the Ashikaga family, serving as shōgun for the Muromachi bakufu, or shogunate, in Kyōto.  The Muromachi period included two sub-periods marking distinct events:  The Nanbokuchō period (1336-1392) and the Sengoku period (1493-1590).

From 1467 to 1477, the Ōnin-Bunmei War (Ōnin-Bunmei no ran) raged in the ancient capital of Kyōto and its environs, marking the beginning of the end for the Muromachi bakufu.  This conflict erupted as several influential clans vied for power during the reign of Ashikaga Yoshimasa, the eighth shōgun, who ruled through the Muromachi bakufu.  The eastern army, led by Hosokawa Katsumoto, fought against the western army, under the command of Yamana Sōzen. Fierce and prolonged battles led to the widespread destruction of Kyōto, not to mention the political, cultural, and social order that it had embodied.  The violence and discord originating in Kyōto engulfed many regions in Japan.

While the bakufu continued to function as a central authority, the conflict undermined its support, and the system of governance began to unravel around 1490.  In 1493, an event known as the Meiō Political Incident (Meiō no seihen) ushered in the Sengoku period.   This incident involved a coup d’etat against Ashikaga Yoshiki, the tenth shōgun, led by Hosokawa Masamoto, the kanrei, or deputy shōgun.  Yoshiki had succeeded Ashikaga Yoshihisa, the ninth shōgun, in 1490, with the support of his aunt, Hino Tomiko, an influential figure in the ruling family for almost forty years.  Meanwhile, Masamoto opposed Yoshiki and his father, Ashikaga Yoshimi, and instead supported Yoshiki’s cousin, Ashikaga Yoshizumi, to become shōgun.  Masamoto opposed orders by Yoshiki for daimyō to join in major military campaigns against the Rokkaku clan and Hatakeyama Yoshitoyo in Kawachi Province. Masamoto then deposed Yoshiki and installed Yoshizumi as the eleventh shōgun.   This divided the Ashikaga family, leading to a loss of control by the officials in Kyōto as well as the shugo, or military governors, who served as their provincial representatives.

In 1568, a triumphal march by Oda Nobunaga and his army to Kyōto, followed by the overthrow of the fifteenth shōgun, Ashikaga Yoshiaki, in 1573, marked the end of the Muromachi period, and the beginning of the Azuchi-Momoyama period.  The Sengoku period concluded with the unification of Japan under Toyotomi Hideyoshi in 1590.  The Azuchi-Momoyama period (1573-1603) partially overlaps with the Sengoku period and ends with the reunification of Japan by Tokugawa Ieyasu.  The Edo period (1603-1868) was marked by the martial rule of the Tokugawa clan based in the Kantō region.

At the regional level, the year marking the beginning of the Sengoku period can be understood as having varied on the basis of local events and ending in the year when a region became subject to a singular authority.  For the Kinai region, the period began with the Meiō Political Incident in 1493 and ended with Oda Nobunaga’s march upon Kyōto and installation of Ashikaga Yoshiaki as shōgun in 1568.   In the Kantō, the Sengoku period began in 1455 when Ashikaga Shigeuji, the fifth Kamakura kubō assassinated Uesugi Noritada, the Kantō kanrei.  The ensuing conflict, known as the Kyōtoku War (Kyōtoku no ran), continued for twenty-eight years.  The Sengoku period came to an end in 1590 with the conquest of Odawara by the forces of Toyotomi Hideyoshi.  In the Tōhoku region, the period began in 1438 with the Eikyō Conflict (Eikyō no ran), an event in which the Kamakura governorate lost control of Mutsu and Dewa provinces.  The period ended in 1590 with the imposition of control over these provinces in an event known as the Oushū Retribution (Ōshū shioki) ordered by Toyotomi Hideyoshi.

Overview

The Sengoku period is noted for pervasive conflict, but it did not occur on a daily basis. Once the traditional authority of the Muromachi bakufu began to wane, persons under the control of military governors and rising powerbrokers formed a new class of provincial rulers.  In a phenomenon known as gekokujō, retainers ousted their lords while acquiring power and influence, and sengoku daimyō arose from a diverse range of circumstances.

During this period, clashes arose from a conflict of interests between lords that originated in the Kinai region and emanated widely throughout the country.  These events undermined the ability of prior rulers to exercise control based on traditional sources of authority.  The rapid development of local economies provided the funds needed to support persistent conflicts.  These activities could not be sustained by relying solely on the currency-based system of trade supported by the provincial organs of the bakufu and the shōen, or private manors, or on the demand from the primary municipalities in Kinai.  The Sengoku period witnessed economic growth during which previously unknown individuals achieved success through a wide variety of means.  In addition to economic development, the flourishing of culture also provided an important backdrop to the period.

The swift and dramatic transformation of societal norms and the collapse of preexisting roles that supported a multilayered structure of land ownership known as the shōen-kōryōsei gave rise to a new form of society.  Rapid economic development spawned a new generation of landowners and merchants.  In the midst of never-ending struggle, a currency-based economy grew as those involved cultivated new lands and engaged in commerce locally and overseas.  Capable citizens demanded a voice in the shaping of society relative to their means and without the traditional restraints of social class.  The economic growth and frequent military clashes led to the formation of independent bodies in the cities, towns, and villages that were equipped to defend their autonomy and development.  These organizations were founded on the basis of a social contract with the townspeople and peasants to protect their rights and, as necessary, to engage in armed conflicts of resistance against outsiders who attempted to impose control over their activities.

The model of governance for daimyō that owned land also transitioned from the former multilayered ownership structure of the shōen to solitary control by the local daimyō.  The territory held by the daimyō reflected the holdings of these independent bodies at the local level.

From the Ōnin-Bunmei War to the Meiō Political Incident

Ashikaga Takauji served as the first shōgun of the Ashikaga bakufu from 1338 to 1358.  During his turbulent reign, the Imperial court stood divided between the Northern Imperial Court, established by Takauji in Kyōtō, and a Southern Imperial Court, established by Emperor Godaigo in Yoshino.  Takauji’s younger brother, Ashikaga Tadayoshi, was a pivotal figure in the bakufu, serving in both an administrative and military capacity at a level making him the de facto head of the bakufu.  Takauji appointed Kō-no-Moronao to serve as the deputy shōgun.  An intrepid character, Moronao served as a general on behalf of the Ashikaga to battle against the loyalist forces of the Southern Court during the wars of the Nanbokuchō period and killed its generals – Kitabatake Akiie and Kusunoki Masayuki.

From late 1350 to early 1352, the bakufu was beset by an internal struggle known as the Kannō Disturbance (Kannō no jōran).  Tensions arose after Takauji appointed Moronao to serve as the deputy shōgun.  Tadayoshi did not get along with Moronao and plotted his assassination.  Following discovery of the plot, in 1350, Moronao compelled Tadayoshi to leave the administration and enter a temple under the monastic name of Keishin.  In 1531, Tadayoshi rebelled against Takauji and Moronao by joining forces with their rivals in the Southern Court.  Serving as a general for the Southern Court, Tadayoshi defeated Takauji’s army, occupied Kyōto, and then entered Kamakura.  During the same year, Tadayoshi’s forces killed Moronao and his brother Moroyasu at Mikage in Settsu Province.  The following year, Tadayoshi was defeated by Takauji at Sattayama.  A reconciliation between the brothers proved to be brief; under seige by Takauji’s armies, he fled to the hills of Izu in 1352.  Shortly after an ostensible second reconciliation, the bakufu army captured Tadayoshi and confined him to the Jōmyō monastery in Kamakura, where he suddenly died, perhaps by poisoning.  The defeat of Tadayoshi and Moronao in the conflict enabled Takauji to retain his role as the shōgun despite lingering resistance from surviving members of Tadayoshi’s faction until 1364.

Generations later, the despotic reign of Ashikaga Yoshinori, the sixth shōgun, resulted in his assassination in an event known as the Kakitsu Disturbance (Kakitsu no ran), triggering a decline of the Muromachi bakufu.  Successive shōgun could no longer exert control over influential military governors in the provinces.  In the Kantō, Ashikaga Shigeuji, the Kamakura kubō, sought refuge in the Koga palace in Shimotsuke Province, assumed the name of the Koga kubō, and initiated a full-scale war against the Uesugi clan who served as the deputy shōgun of the Kantō, a nearly three-decade rift known as the Kyōtoku War running from 1455 to 1483.  During this period, Ashikaga Yoshimasa, the eighth shōgun, dispatched his half-brother, Ashikaga Masatomo, to Kamakura with the aim of installing him as the next Kamakura kubō.  Unable to enter Kamakura, Masatomo constructed a palace in Izu and became the Horigoe kubō.  Meanwhile, battles erupted between influential families in Yamato and Kaga provinces, while frequent protests broke out even in the shōgun’s seat of power in Kyōto, fueled by dissatisfaction among locals with the inability of the shōgun to address crop failures, epidemics, and other societal ills.

During Yoshimasa’s reign, fault lines began to emerge along east-west lines, including succession struggles within not only the shōgun’s family, but within other powerful clans such as the Hatakeyama and the Shiba, while provincial military governors such as the Yamana and Hosokawa vied against one another to expand their domains.  These tensions culminated in the Ōnin-Bunmei War.  Powerful provincial clans such as the Ōuchi and the Wakasa-Takeda converged upon the capital of Kyōto, which became a central battleground for a calamitous period running from 1467 to 1478.  The conflict led to the decline of the Yamana clan, the withdrawal from the capital of key elements of the western army such as the Ōuchi, and the cementing of political power by the Hosokawa.  Nevertheless, the western and eastern armies suffered mutual losses, and without a decisive victor, instability continued.  At the height of the conflict, the absence of provincial military governors from their home bases created opportunities for deputy military governors to seize local control, an illustration of the phenomenon known as gekokujō.  Meanwhile, forces entered the territories of their rivals to stir confusion and conflict and as a means to undermine the historical governance of the bakufu in the provinces.

Even after the Ōnin-Bunmei War, the bakufu retained some elements of authority.  In 1487, daimyō from provinces near the capital such as Owari and Wakasa came to the support of the shōgun in response to an attack by Rokkaku Takayori from Ōmi Province.  Many daimyō helped defend Ashikaga Yoshiki, the tenth shōgun, against an invasion of Kawachi Province in 1492. However, in the midst of the invasion, Hosokawa Masamoto, the deputy shōgun, orchestrated a successful coup d’état against Yoshiki, and seized leadership of the bakufu on behalf of the Hosokawa clan.  This momentous event, known as the Meiō Political Incident, served as the opening chapter of the Sengoku period and subordinated the role of the shōgun to that of a puppet of the Hosokawa.  Following the assassination of Masamoto at the hands of some of his retainers, a succession struggle ensued among his adopted sons, with Hosokawa Sumimoto and his son Hosokawa Harumoto pitted against Hosokawa Takakuni and his supporters.  The internal discord contributed to a decisive loss of central authority by the bakufu.  Aspiring to restore his position as the shōgun, Ashikaga Yoshiki became dependent upon assorted daimyō, while the influence of the bakufu was limited to Yamashiro Province.  Wealthy provincial families either reserved their resources or leaned on other influential clans for support.  Meanwhile, the fluid state of affairs enabled numerous capable individuals, such as Hōjō Sōun and Saitō Dōsan, to rise from humble origins to become sengoku daimyō having control over expansive domains.

From the Meiō Political Incident to the advent of Oda Nobunaga

In the Meiō Political Incident, Hosokawa Masamoto banished Ashikaga Yoshiki (the shōgun and son of Ashikaga Yoshimi) and installed Ashikaga Seikō (later known as Ashikaga Yoshizumi) as his successor.  Yoshiki sought refuge in territories outside of the capital, while competing factions formed in the provinces in the Kinki Region with some in support of Yoshiki and others in support of Yoshizumi.  Having evinced a tyrannical style of governance, in 1507, Hosokawa Masamoto was struck down by Kōzai Motonaga and Yakushiji Nagatada, giving rise to a prolonged succession struggle known as the Eishō Disturbance (Eishō no sakuran).  Masamoto had three adopted sons (Sumiyuki, Takakuni, and Sumimoto).  Soon after the killing, Takakuni eliminated Sumiyuki, after which factions supporting Takakuni clashed with those who favored Sumimoto.  Eyeing an opportunity, Ōuchi Yoshioki from Suō Province traveled to Kyōto in support of Ashikaga Yoshitada (the former shōgun earlier known as Ashikaga Yoshiki and later known as Ashikaga Yoshitane). Takakuni joined with Yoshioki in support of Yoshitada, whereupon Sumimoto sided with Yoshizumi in opposition to them. Yoshizumi’s death in 1511 led to a decline in the faction supporting Sumimoto, and while Sumimoto made numerous trips to the capital from his base in Awa Province on the island of Shikoku, in the end he could not wrest control away from Yoshitane and died in Awa in 1520.

After Sumimoto’s death, a timeline of notable events includes:

• In 1521, Hosokawa Takakuni banished Ashikaga Yoshitane and installs Ashikaga Yoshiharu (Yoshizumi’s son) as shōgun.
• In 1526, Yanagimoto Kataharu, who served on behalf of Hosokawa Harumoto (Sumimoto’s son) and Ashikaga Yoshitsuna, engaged in battle against Takakuni.  Kataharu succeeded in taking control of the environs of Kyōto but was later assassinated in 1530.
• In 1531, Takakuni and Uragami Muramune from Harima Province died in battle at the Tennō temple, after which Harumoto seized political power.
• In 1543, Hosokawa Ujitsuna engaged in battle against Harumoto, who had been named as successor to Takakuni.
• In 1547, Miyoshi Nagayoshi estranged himself from Harumoto and joined forces with Ujitsuna.
• In 1548, Nagayoshi banished Harumoto and Yoshiharu from Kyōto.
• In 1552, Nagayoshi reconciled with Ashikaga Yoshifuji (later known as Ashiakaga Yoshiteru).  Nagayoshi later died in 1564.
• In 1565, Yoshiteru was assassinated by Miyoshi Yoshitsugu, the Miyoshi Group of Three (Miyoshi Nagayasu, Miyoshi Masakatsu, and Iwanari Tomomichi), and Matsunaga Hisamichi in an event known as the Eiroku Incident (Eiroku no hen).
• In 1566, the Miyoshi Group of Three confronted Matsunaga Hisahide, triggering conflict across the Kinai.
• In 1568, Oda Nobunaga marched upon Kyōto in support of Ashikaga Yoshiaki as the next shōgun.

As noted above, political control transferred from the Ashikaga to the Hosokawa, followed by the Miyoshi clan.  As deputy shōgun, the Hosokawa were vested with formal powers of governance.  The Miyoshi, however, were a wealthy family from Muya in Awa Province who served as retainers of the Hosokawa and therefore not well-positioned to lead the Muromachi bakufu in the capital of Kyōto.  This made clear the loss of authority of the bakufu, creating a political vacuum that gave rise to sengoku daimyō such as Takeda Shingen, Uesugi Kenshin, Hōjō Ujiyasu, Ōtomo Yoshishige, Shimazu Takahisa, and many others vying for power and influence throughout the country.

Miyoshi Nagayoshi leveraged a powerful army to take control of the capital and its environs and expel the Ashikaga clan.  The Miyoshi administration, however, failed to gain legitimacy among the populace, inviting resistance from local families of influence.    Following the death of Nagayoshi, the Miyoshi were led by Miyoshi Yoshitsugu.  His inexperience contributed to a weakening of their authority, whereupon Ashikaga Yoshiteru aspired to restore the Ashikaga as the shōgun.  In response to this threat to their authority, the Miyoshi had Yoshiteru killed in an act known as the Eiroku Incident (Eiroku no hen).  Nevertheless, the Miyoshi then ceded authority to the capital to Oda Nobunaga after he marched upon Kyōto to install Ashikaga Yoshiaki with the support of Matsunaga Hisahide, Azai Nagamasa and the Kōfuku Temple.  In the end, the Miyoshi’s grip on power did not last more than four years.

After the advent of Oda Nobunaga

In 1560, Oda Nobunaga from Owari Province defeated Imagawa Yoshimoto in a surprise attack at the Battle of Okehazama.  In 1567, he captured Minō Province from the Saitō clan, and, in 1568, led a large contingent to Kyōto to install Ashikaga Yoshiaki (the younger brother of Ashikaga Yoshiteru) as the next shōgun.  Nobuanaga issued a proclamation in the name of Yoshiaki to all surrounding daimyō to mark his ascendance to power.  After taking control of the capital, Nobunaga added the commercial centers of Ōzu, Sakai, and Ōyamazaki to his domain.  He also gave permission for Luís Fróis, a Jesuit missionary from Portugal, to reside in the capital and to evangelize the Jesuit religion.

During this period, provincial daimyō also expanded their influence.  After the Battle of Okehazama, Tokugawa Ieyasu left the protection of the Imagawa and recovered Mikawa Province, a former territory of the Matsudaira clan.  Other influential daimyō included the Gohōjō of the Kantō, the Takeda of Kai and Shinano provinces, the Uesugi in the Hokuriku region, the Mōri of the Chūgoku Region, the Chōsokabe of Shikoku, and the Shimazu of Kyūshū.  Some of these daimyō allied with Nobunaga, while others allied with other daimyō in opposition to the Oda.

After a falling out with Nobunaga, Yoshiaki took the lead to form an anti-Nobunaga faction comprised of the adherents of Ishiyama-Hongan Temple based at Mount Hiei, the Hongan Temple, Takeda Shingen, Uesugi Kenshin, Mōri Terumoto, Asakura Yoshikage, Azai Nagamasa, Matsunaga Hisahide, and the Miyoshi Group of Three and together planned to encircle Nobunaga.  Attacks by the powerful Oda army caused the coalition to collapse and Yoshiaki was driven out of the capital.  Remnants of the bakufu gathered in the town of Tomo in Bingo Province.  Meanwhile, monks affiliated with the Ishiyama-Hongan Temple of the Jōdo-Shinshū sect launched resistance campaigns in numerous provinces.  The Ishiyama-Hongan Temple fought incessantly against Nobunaga for over a decade.  Nevertheless, the Oda defeated the opposition parties one after another, and, by 1582, had consolidated control of central Japan.  While on the verge of unifying the country, Nobunaga and his eldest son, Nobutada, were killed in a dramatic coup d’état known as the Honnō Temple Incident, orchestrated by Akechi Mitsuhide, one of Nobunaga’s most senior commanders.

Within weeks after the death of Nobunaga, Hashiba Hideyoshi (later known as Toyotomi Hideyoshi) led a rapid march of forces from the western provinces to defeat Mitsuhide at the Battle of Yamazaki on the border of Settsu and Yamashiro provinces.  The following year, Hideyoshi then prevailed against Shibata Katsuie at the Battle of Shizugatake to claim the role as the most powerful warlord in the country.  At the Kiyosu Conference, Hideyoshi cemented his position by backing Nobunaga’s lineal grandson, Sanpōshi (later known as Hidenobu), as the successor.  However, the disintegration of the Oda administration and rise of the Toyotomi administration caused tensions, and, in 1584, Hideyoshi had a falling out with Oda Nobukatsu (Nobunaga’s second son).  Sanpōshi moved from the Oda base at Azuchi Castle to Sakamoto Castle, and thereafter to Kyōto under the watch of Hideyoshi.  Nobukatsu joined with Tokugawa Ieyasu in revolt, while mercenaries known as the Saika Group, the Negoro Group, Hōjō Ujimasa, Chōsokabe Motochika, and Sasaki Narimasa formed an array of opposition to Hideyoshi.  As disputes arose in regard to the battlefront, Hideyoshi appeased Nobukatsu and the enemy forces withdrew.  Ieyasu submitted to Hideyoshi and then played an important role in the Toyotomi administration.

Hideyoshi received the surname of Toyotomi and awarded the title of kanpaku, or Chief Advisor to the Emperor, giving further legitimacy to his administration.  Hideyoshi issued a directive prohibiting personal conflicts between the provincial daimyō, thereby nominally unifying the entire country.  Hideyoshi ordered a country-wide land survey, unified the currency, prohibited the possession of swords by persons other than bushi, and issued a law prohibiting persons who served military families from fleeing to join other families, or for peasants to leave their occupations and engage in commerce.  In 1590, he decimated the Gohōjō at the Conquest of Odawara, effectively bring the country under his governance.  From 1592 to 1597, Hideyoshi’s forces crossed the Sea of Japan to invade the Korean Peninsula in the Bunroku and Keichō expeditions, but following his death in 1598, the forces withdrew in defeat.  Relations with Korea resumed in the early part of the Edo Period through the Sō clan in Tsushima Province.

After the demise of Hideyoshi, senior leaders in the Toyotomi administration vied for control.  In 1600, Tokugawa Ieyasu led the Eastern Army to victory against Ishida Mitsunari of the Western Army at the Battle of Sekigahara in Minō Province.  After the war, Ieyasu exercised his authority as the supreme commander of the Eastern Army to forcibly relocate certain daimyō and to demote others according to his orders.  In 1603, Ieyasu was awarded the title of Supreme General (seiitai-shōgun) and formed the Edo bakufu.  In 1605, he assigned the role of shōgun to his third son, Tokugawa Hidetada, and made clear to the daimyō that the role of the shōgun would be transferred only through hereditary succession.  In 1615, he ordered daimyō to abandon castles other than their home bases with the aim of reducing conflicts.  Ieyasu continued to exert influence in his role as a retired leader, reassigning and demoting daimyō at his discretion.

From 1614 to 1615, Ieyasu’s army laid siege to Toyotomi Hideyori at Ōsaka Castle in summer and winter campaigns, resulting in decimation of the Toyotomi clan.   An event known as the Hōkō Temple Bell Inscription Incident served as a pretext for the attack.  In this incident, Ieyasu ordered Hideyori to reconstruct a Buddhist statue at the Hōkō Temple including the casting of a bell.  Hideyori had the bell inscribed in a manner interpreted by Ieyasu as a curse on the Tokugawa and as good fortune for the Toyotomi.  Unable to reconcile their differences, the two sides slid into conflict at Ōsaka Castle.

Sengoku Daimyō

Sengoku daimyō primarily originated from military governors (shugo daimyō), deputy military governors (shugodai), or local lords (kokujin).  Others were provincial governors (such as the Kitabatake clan) or nobles (such as the Ichijō clan from Tosa Province).  On rare occasions, even individuals of low social status (such as Toyotomi Hideyoshi) ascended through their own merit to become sengoku daimyō.  In the Sengoku period, there were many instances where persons of lesser status usurped those above them in a phenomenon known as gekokujō.

Sengoku daimyō exercised a high degree of autonomy and unitary governance in their respective domains, akin to feudal states.  However, the sengoku daimyō were not always transcendental figures.  Retainers comprised of local lords and servants served as their primary base of political and military support, and interdepedent relationships with these classes were essential to maintain their grip on power.  Sengoku daimyō who failed to protect the interests of their retainers were frequently overthrown.

Regional circumstances during the Sengoku period

The Ouu Region (Mutsu Province (Oushū) and Dewa Province (Ushū) in Northern Japan)

Many of the sengoku daimyō in the Ouu region originated from hereditary landowners dating to the Kamakura period.  The Kakizaki clan, descendants of the Wakasa-Takeda, were a notable exception, having governed wealthy families along the Tsugaru Straits between the islands of Hokkaidō and Honshū.

Sengoku daimyō in the Ouu region avoided most of the conflict occurring in the Kantō as well the political disputes among the central authorites in Kyōto.  In terms of warfare, beginning in the first half of the fifteenth century, the Nanbu clan made expeditions to Senboku and Kazuno, engaging in battle into the Eiroku era (1558 – 1570).  An invasion by the Date clan into the Kahoku area served as another notable territorial conflict.  Others such as Ashikaga Mitsunao (the Sasagawa kubō) and the Shiba clan were decimated, demonstrating that the Tōhoku region was not entirely peaceful.  Moreover, in 1522, Date Tanemune (a sengoku daimyō and fourteenth head of the Data clan) disregarded the Ōsaki clan who served as representatives of the Muromachi bakufu in Oushū, and assumed the position of military governor of Mutsu Province as another example of the usurpation of the ruling class.

Political marriages among local rulers in the southern districts of the Ouu region were common, and in cases when daimyō did not have natural successors, designated successors were typically adopted from the families of other daimyō instead of from among the commoners.  In one case, the eldest son of Date Harumune (the fifteenth head of the Date clan) succeeded Iwaki Shigetaka, his maternal grandfather.  The eldest son of Nikaidō Moriyoshi was tendered as a hostage after a defeat to the Ashina clan and, after the early demise of the head of the clan, became the adopted heir to its leader and assumed the name of Ashina Moritaka.  Even in cases when discord between assorted daimyō escalated into battle, blood relatives of the feuding parties frequently intervened to enable reconciliation prior to the decimation of either clan.

In 1542, a dispute arose between Data Tanemune and his son regarding the order of succession in the family, escalating into the Tenbun Conflict (Tenbun no ran) which embroiled other blood-related daimyō in Ouu over a six-year period.  In the course of this conflict, Date Harumune formed a pact with local rulers, enabling him to establish a system of governance with himself as a sengoku daimyō in advance of other daimyō in the Ouu region.

Thereafter, families such as the Ashina, the Tamura, the Iwaki, the Mogami, and the Nanbu formed their own relationships with local lords and daimyō to become sengoku daimyō.  Official recognition by the Muromachi bakufu of the authority of the sengoku daimyō to conduct security operations, raise armies, and collect taxes spurred the centralization of power in each province.  In 1590, an expedition by Toyotomi Hideyoshi to the northern provinces known as the Oushū Retribution (Ōshū shioki) resulted in recognition of the pre-exisiting rights of the sengoku daimyō in exchange for their allegiance to the Toyotomi administration.

Written proclamations from the latter part of the sixteenth century provided recognition of the right to land ownership by the shogunate including: for the Andō clan (the Akita District), for the Sannohe-Nanbu clan (the Nukanobu District), for the Ōsaki clan who were local commissioners of Ōshū for the shogunate (the Ōsaki area), for the Kasai clan (the Tome District), for the Mogami clan who were local commissioners of Ushū for the shogunate (the Mogami and Murayama regions), for the Date clan (the Shinobu District, the Date District,  the Okitama District, the Katta District, the Shibata District, and the Miyagi District), for the Ashina clan (Aizu, the Yama District, the Ōnuma District, the Kawanuma District, the Kanbara District, the Asaka District, the Iwase District), for the Nihonmatsu clan (the Adachi District), for the Tamura clan (the Tamura District), for the Ishikawa clan and the Shirakawa-Yūki clan (the Shirakawa District), for the Sōma clan (the Namekata District, the Uda District, the Shineha District), and for the Iwaki clan (the Naraha District, the Iwaki District, the Iwasaki District, the Kikuta District, and the Taga District).

In the 1580’s, Date Masamune exercised his military skills to consolidate control of the southern districts of the Ouu region.  Prior to these developments, Satake Yoshishige (a sengoku daimyō from Hitachi Province) governed the daimyō and was in the process of consolidating control of this same area.  The succession to Masamune was carried out in circumstances where the influence of the Satake clan extended north to the domain of the Date.  An effort by the Date to protect the home of Masamune’s formal wife (the Tamura clan) which was under the control of daimyō governed by the Satake posed a challenge to Yoshishige’s governance of Oushū, and in the end he yielded his position to the Date.

The Kantō Region

Prior to the Ōnin-Bunmei War, the Kantō witnessed a series of major battles including the Kyōtoku War, the Chōkyō Conflict, and the Eishō Conflict.  These arose out of a three-way power struggle between the Koga kubō, the Yamauchi-Uesugi family who served as the deputy shōgun of Kantō, and the Ōgigayatsu-Uesugi family who were a non-lineal branch of the Yamanouchi-Uesugi family.

Ise Shinkurō Moritoki (later known as Hōjō Sōun), lord of Kōkokuji Castle and an uncle of Imagawa Ujichika, joined a rebellion that followed the death of Ashikaga Masatomo who had served as the Horigoe kubō in Izu Province.  In 1493, Sōun eliminated Ashikaga Chachamaru (who had served as Masatomo’s successor) and pacified Izu Province.  Thereafter, his children adopted the surname of Hōjō.  The Hōjō initially vied against the Uesugi clan for control of the Kantō Region, but, in 1546, the Uesugi lost power after defeat at the Siege of Kawagoe Castle.  In 1552, the Hōjō captured the Koga palace and seized control of the Koga kubō.  The Yamanouchi-Uesugi were driven out of Kōzuke Province and received support from Nagao Kagetora (later known as Uesugi Kenshin) whereupon the Hōjō and the Nagao (later adopting the Uesugi name) continued to battle for control of the Kantō.

After becoming successor to the position of deputy shōgun of Kantō, Uesugi Kenshin surrounded the Hōjō at Odawara Castle, but did not capture it.  The conflict between the Uesugi and the Hōjō divided powerful families across Kantō, triggering confrontations such as the Battle of Kōnodai between Hōjō Ujiyasu and Satomi Yoshitaka (on behalf of the Uesugi) throughout the region.  In 1579, following the death of Uesugi Kenshin, clans including the Satake of Hitachi Province, the Satomi of Awa Province, and the Utsunomiya of Shimotsuke Province resisted invasions by the Hōjō, but could not prevent an expansion of the territory controlled by the Hōjō.  Meanwhile, advances by the Date clan in Oushū led to inevitable conflict against Satake Yoshishige in both the southern and northern areas of the region.

In 1582, at the Conquest of Kōshū, the Oda, the Tokugawa, and the Gohōjō clans attacked the Takeda clan in Kai, Shinano, and Suruga provinces.  However, after the coup d’état that resulted in the unexpected death of Oda Nobunaga, the Gohōjō abandoned their alliance with the Oda and invaded Kai and Shinano in the Battle of Kannagawa.  Competition among the Tokugawa, the Uesugi, the Gohōjō, and the Sanada for the former territory of the Takeda gave rise to the Battle of Tenshō-Jingo.  As an outcome of this conflict, the Tokugawa controlled Kai and southern Shinano, the Uesugi controlled northern Shinano, the Gohōjō controlled Kōzuke, and the Sanada controlled Numata Castle in the Tone District of Kōzuke.

In 1590, Toyotomi Hideyoshi issued a proclamation to prohibit personal conflict between daimyō.  An invasion by retainers of the Gohōjō into the territory held by the Sanada violated this rule, whereupon the Toyotomi led an allied army of 210,000 men to surround Hōjō Ujinao (a sengoku daimyō) at his base at Odawara Castle in Sagami Province in an event known as the Conquest of Odawara.  The inevitable fal of the castle accompanied a decimation of the Hōjō clan, marking a unification of the country under Toyotomi Hideyoshi.  The Toyotomi procxeeded to seize the territory of numerous daimyō from Kantō who had supported the Hōjō while well-known families dating from the Kamakura period such as the Oyama and Chiba were eliminated.   Meanwhile, in the autumn of 1590, Tokugawa Ieyasu moved his residence to Edo Castle in Kantō.

After the Battle of Sekigahara in 1600, Tokugawa Ieyasu founded the Edo bakufu in 1603, and in the process of establishing the Edo bakufu as a successor to the Toyotomi administration, clans including the Satake, the Satomi, and the Utsunomiya were either forcibly reolocated or demoted, and no longer maintained a presence in the Kantō.  The Edo bakufu then oversaw a period of relative peace for over fifteen generations until the Meiji Restoration in 1868.

The Northern Kantō Region

The outcome of the Kyōtoku War, the Chōkyō War, and the Eishō Conflict extended to the northern Kantō where the Shimotsuke-Utsunomiya, the Satake, and the Shirakawa-Yūki vied against one another for control.

In the wake of the Eishō Conflict, in 1506, an internal conflict broke out in the family of the Koga kubō.  Ashikaga Masauji (the Koga kubō) had a falling out with his eldest son and heir, Ashikaga Takamoto.  Masauji was supported by daimyō such as Oyama Shigenaga of Shimotsuke, Satake Yoshikiyo of Hitachi, and Nasu Sukefusa of Shimotsuke, while Takamoto received backing from blood relatives led by Utsunomiya Shigetsuna (his father-in-law) of Shimotsuke, Nasu Sukechika of Shimotsuke, Yūki Masatomo of Shimōsa, and Oda Shigeharu and Oda Masaharu (father and son) of Hitachi.  This internal conflict had implications for the southern areas of the Kantō as well as Ōshū.  Iwaki Yoshitaka and Yūki Akiyori from the southern portion of Mutsu Province suported Masauji, while Takamoto was supported by Date Tanemoto of Oushū, Hōjō Sōun and Hōjō Ujitsuna (father and son) of Sagami, and Chiba Katsutane and Chiba Masatane (father and son) of Shimōsa.  Internal conflicts also arose among military families who had close relations with the Ashikaga family of the Koga kubō including within the Yamauchi-Uesugi family, the Eishō Discord within the Shimotsuke-Utsunomiya clan, and conflicts within the Nasu and Shirakawa-Yūki clans.  During this period, the northern Kantō was beset by widespread conflicts.

In the earlier part of the Sengoku period, after Utsunomiya Shigetsuna of the Shimotsuke-Utsunomiya prevailed in the Utsunomiya Disturbance (Utsunomiya sakuran) and Satake Yoshikiyo of Hitachi prevailed in an internal conflict in the Satake clan, Shigetsuna and Yoshikiyo vied for control of northern Kantō.  The Satake clan experienced temporary setbacks after their defeat at the Battle of Takebayashi in 1514 and the Battle of Nawazuri in 1516.  Meanwhile, Ashikaga Takamoto secured his position as the third Koga kubō with the support of Shigetsuna.  The expanding influence of the Shimotsuke-Utsunomiya and loss of power by neighboring clans enabled Shigetsuna to garner control of Northern Kantō and exert a major influence on the region.  The families who had supported Masauji in the Eishō Conflict experienced a decline in influence, while the Gohōjō who had supported Takamoto advanced into northern Kantō.  In 1514, a branch of the Nasu clan aligned with the Muromachi bakufu collapsed from internal discord.  Shigetsuna attempted to intervene, but, fearing a takeover, Nasu Shigefusa from the family aligned with the Koga kubō swiftly took over and unified the clan which had earlier been divided.   Thereafter, the unified Nasu clan fought incessantly against the Utsunomiya and Satake clans.

Following the demise of Shigetsuna, the Utsunomiya clan of Shimotsuke gradually lost its cohesiveness, and during the Daiei era (1521 to 1528), an internal conflict arose.  Senior retainers including the Haga, the Shioya, and the Kasama, in addition to allies including the Yūki, joined forces and, in 1523, Yūki Masatomo defeated Utsunomiya Tadatsuna at the Battle of Saruyama, and supported Utsunomiya Okitsuna as his successor.  A loss of influence by the Shimotsuke-Utsunomiya provided an opportunity for the Gohōjō to advance into northern Kantō and for bands of retainers to exhibit tyrannical behavior.  During this period, the actions of Yūki Masatomo and Yūki Masakatsu (father and son) of the Yūki clan along with Oda Masaharu of the Oda clan featured prominently.

At this time, the Koga kubō represented the position of highest authority in the Kantō, and to maintain the hegemony, the influence of the Koga kubō was essential.  The Koga kubō received the backing of Utsunomiya Shigetsuna (an advocate of Ashikaga Takamoto), Hōjō Ujiyasu (an advocate of Ashikaga Yoshiuji), and Uesugi Kenshin (as advocate of Ashikaga Fujiuji).  However, in the latter part of the Sengoku period, the Koga kubō lost unanimous support from among the daimyō of the Kantō, and it experienced a weakening of its authority.

Owing to internal conflicts, the Satake, the unified Nasu, the Oyama, and the Shimotsuke-Utsunomiya fell significantly behind the Gohōjō in the quest for influence.  To respond to an invasion by Hōjō Ujimasa into northern Kantō, military families in Kantō sought the support of Uesugi Kenshin from Echigo Province who held the title of deputy shōgun of Kantō.  Despite multiple internal rebellions, the Satake steadily reconstituted the clan and restored their power under Satake Yoshiaki.  In 1558, Yoshiaki successfully combined with Haga Takasada in a bid to recapture Utsunomiya Castle which had earlier been taken by Mibu Tsunafusa and Mibu Tsunatake (father and son).  Afterwards, he had his daughter, Nanryoin, wed to Utsunomiya Hirotsuna (the twenty-first head of the Utsunomiya clan) in a political marriage.

In the latter part of the Sengoku period, the Gohōjō advanced into northern Kantō.  Conflict spread across the region as the Satake, the Utsunomiya, and the Oyama under the leadership of Uesugi Kenshin opposed the Gohōjō who were supported by the Yūki, the Nasu, the Oda, and the Mibu clans.  Meanwhile, the Sano, the Minagawa, and the Yokose clans deftly switched allegiances to survive the tumult.  The Mibu clan fractured, with forces led by Mibu Kanetake (the younger brother of Mibu Tsunafusa) surrendering to the Utsunomiya so that the Mibu forces based at Kanuma Castle aligned with the Utsunomiya while the Mibu forces at Mibu Castle aligned with the Hōjō.  However, in 1576, Mibu Yoshitake (the son of Mibu Tsunatake) killed Kanetake and re-unified the clan.

Following the death of Uesugi Kenshin in 1579, Satake Yoshishige led other daimyō in Kantō to resist an invasion by Hōjō Ujinao.  This band gradually lost ground after the Battle of Numajiri and other engagements against the Gohōjō.  Meanwhile, after the death in battle of Sano Munetsuna, the Sano clan was subject to intervention by the Gohōjō and compelled to accept one of their members as their new leader.  Oyama Hidetsuna was attacked at Oyama Castle in Shimotsuke Province by the Gohōjō.  The Satake clan expanded their influence to Aizu and took command of the Ashina clan, while Date Masamune led forces from Ōshū toward the southern area, so attacks came from both north and south.  After the Gohōjō suppressed the southern portions of Shimotsuke, the Utsunomiya domain became the front line of attacks by the Nasu, the Mibu, and the Minagawa in addition to an assault by the Hōjō army against Utsunomiya Castle.  As further evidence of the dire situation, Utsunomiya Kunitsuna transferred his base from Utsunomiya Castle to the well-fortified Tage Castle.

Numerous daimyō including Satake Yoshishige, Yūki Harutomo, and Utsunomiya Kunitsuna supported Toyotomi Hideyoshi in the Odawara Expedition.  After the conflict, Hideyoshi recognized their right to land ownership in the Utsunomiya Pacification (Utsunomiya shioki) in the summer of 1590.  However, assorted clans such as the Oyama, the Oda, the Mibu, and the Daijō were vanquished.  Meanwhile, Ōzeki Takamasu, Ōtawara Harukiyo, Okamoto Masachika, and Mizunoya Masamura became independent daimyō under the Toyotomi.  Nasu Sukeharu was initially demoted, but, through the effort of Takamasu and others, was able to regain his position as a daimyō of the Toyotomi on the condition that Nasu Sukekage serve as the head of the Nasu clan.  Yura Kunishige supported the Gohōjō, holing-up in Odawara Castle to resist the Toyotomi, however, after his eldest son, Yura Sadashige, deployed with the Toyotomi, Kunishige was forgiven and allowed to serve as a daimyō for the Toyotomi.  After surrendering to Tokugawa Ieyasu, Minagawa Hiroteru was also forgiven by Hideyoshi and became a daimyō of the Toyotomi.  The Utsunomiya clan was swept-up in internal conflicts between Asano Nagamasa, Ishida Mitsunari and others within the Toyotomi administration, and, based on charges of falsifying rice yields, was demoted in 1597.  The Satake clan appeared to be next in line for expulsion, but were spared through the offices of Ishida Mitsunari.

The Chūbu Region

The military governors in Kai and Shinano provinces were in a weakened state, while local clans of influence vied for control.

The Takeda clan, who descended from the Kai-Genji and served as the military governor of Kai, collapsed as a result of the Uesugi-Zenshū Conflict in 1416.  This led to an unstable situation in Kai persisting into the Sengoku period, with the Ogasawara serving as the military governor in the provincial capital of Fuchū, the Murakami and Takanashi clans in northern Kai, the Unnō in eastern Kai, the Nishina in the Azumi district, the Suwa in the Suwa district, and the Kiso in the Kiso district all competing against one another for power and influence.

Ultimately, Takeda Nobutora garnered control of Kai, designated Kōfu as his base, reconciled with daimyō in neighboring provinces, and launched an invasion of Shinano.  Owing to a rebellion by his eldest son, Takeda Harunobu (known as Shingen) and senior retainers, Nobutora was compelled to seek refuge in Suruga Province in 1541.

Takeda Shingen intensified the invasion of Shinano earlier initiated by Nobutora, and after entering into a three-way alliance with Hōjō Ujiyasu of Sagami Province and Imagawa Yoshimoto of Suruga Province, launched an attack in Suwa.  The Ogasawara and Murakami were expelled while Shinano fell under Takeda control.  Shingen became the military governor of Shinano and battled repeatedly for over ten years against the Nagao (the Uesugi clan) of Echigo Province who protected influential families in northern Shinano in a protracted conflict known as the Battle of Kawanakajima.

Thereafter, the Takeda broke the three-way alliance and, after the defeat of Imagawa Yoshimoto at the Battle of Okehazama, invaded the Imagawa territory in Suruga, later confronting the powerful Oda of Owari Province and the Tokugawa of Mikawa Province.  In the autumn of 1572, Shingen launched the Western Expedition to attack the Tokugawa in Mikawa.  The invading army, however, was forced to retreat after the sudden death by illness of Shingen during an assault against Noda Castle.

In 1575, the Battle of Nagashino witnessed an army led by Takeda Katsuyori fight against allied armies under Oda Nobunaga and Tokugawa Ieyasu in the environs of Nagashino Castle in Mikawa Province.  A major loss by the Takeda rattled their domain, and, in 1582, Kiso Yoshimasa, landowner of the Kiso Valley, betrayed the Takeda in favor of Oda Nobunaga.  An army dispatched by Katsuyori to challenge the Kiso was forced to retreat in defeat.  Meanwhile, Anayama Nobutada, a relative of the Takeda, rebelled against his former master, while Katsuyori further suffered incursions into his territory by Tokugawa Ieyasu and Hōjō Ujimasa who were allied with the Oda.  Unable to mount a successful defense, Takeda Katsuyori and his son, Takeda Nobukatsu, were chased away by an army led by Oda Nobutada.  In 1582, in a conflict known as the Kōshū Expedition (kōshū seibatsu), Katsuyori and Nobukatsu took their lives on Mount Tenmoku and the Takeda clan collapsed.

Following the demise of the Takeda clan, Oda Nobunaga assigned one of his senior commanders, Takigawa Kazumasu, to govern Kai and Shinano.  Soon thereafter, Nobunaga was killed in a dramatic coup d’état known as the Honnō Temple Incident (Honnōjij no hen), whereupon the Gohōjō invaded and caused the Takigawa to retreat in the Battle of Kannagawa.  In the same period, the Tokugawa, the Gohōjō, the Uesugi, and Sanada Masayuki fought over a wide area in the former territory of the Takeda in a four-month engagement known as the Battle of Tenshōjingo.  In the wake of the conflict, the Tokugawa took control of Kai and Shinano while the Uesugi occupied northern Shinano.  The Toyotomi administration compelled the Tokugawa and numerous influential families from Shinano to relocate to the Kantō, but former retainers of the Takeda such as the Sanada rose to become daimyō.  Hoshina Masayuki, an illegitimate son of Tokugawa Hidetada, became the head of the Hoshina in the Takai district of northern Shinano while the Ogasawara were ordered to perform a significant role in Kyūshū on behalf of the Tokugawa shogunate in the Edo period.

The Hokuriku Region

In the Hokuriku region, the Uesugi (Nagao) governed Echigo Province, the Jinbō and Shiina in Etchū, the Hatakeyama in Noto, the Asakura in Echizen, and the Ikkō-ikki of Kaga.

In Echigo, the Nagao clan rose from their position of deputy military governors to usurp the authority of the Uesugi.  By 1576, Nagao Kagetora (later known as Uesugi Kenshin) from the Nagao clan nearly controlled the Hokuriku region.

In Etchū, the Jinbō joined with their former enemies, the Ikkō-ikki of Kaga, but were conquered by allied forces comprised of the Uesugi of Echigo, the Hatakeyama military governors of Noto.  The Hatakeyama were troubled by the despotic behavior of senior retainers such as the Chō clan, causing a series of internal disputes.  In 1576, the Hatakeyama surrendered to the Uesugi of Echigo and were vanquished as a clan.

In Echizen, the Asakura clan toppled the Shiba and repelled the Ikkō-ikki.  The clan flourished in their home territory of Ichijōdani, welcoming nobles from Kyōto and cultivating a sophisticated culture unique to the region in this period.  Ultimately, in 1573, the Asakura incurred an attack by Oda Nobunaga, and even with the support of forces supplied by Azai Nagamasa, lost at the Siege of Ichijōdani Castle (also known as the Battle of Tonezaka).  Asakura Yoshikage, the head of the clan, killed himself and the Asakura were extinguished.  Thereafter, the Oda assigned Maeba Yoshitsugu to protect the captured castle and territory, but Toda Nagashige joined forces with the Jōdo sect of the Hongan Temple to launch a resistance in Echizen.  However, opposition among members of the sect to the tyrannical rule of their head priest, Shimotsuma Raishō, caused internal conflicts creating an opportunity for the Oda to invade and pacify the resistance over a two-year period.

In Kaga Province, the Ikkō-ikki of Kaga overthrew the Togashi clan and formed a self-governing empire for the Hongan Temple that lasted for one hundred years.  The Ikkō-ikki of Kaga fought against the Uesugi and other clans, ultimately losing to the Oda army under the command of Shibata Katsuie, drawing to an end their extended period of self-rule.  Thereafter, the Ikkō-ikki continued to engage in the conflict between the Ishiyama-Hongan Temple and Nobunaga for the next ten years.

The Tōkai Region

Early in the Sengoku period, the Tōkai region was governed by provincial daimyō, including the Toki clan in Mino, the Shiba in Owari and Tōtōmi, the Matsudaira in Mikawa, and the Imagawa in Suruga.

In Mino, upon the escalation of an internal dispute in the Toki clan, Saitō Toshimasa (later known as Saitō Dōsan) saw an opportunity to ingratiate himself with his lord, Toki Yoriaki, whereupon, in 1542, he usurped Yoriaki and seized control of Mino.  With the support of Oda Nobuhide, Yoriaki and Asakura Takakage invaded Mino, but Dōsan led a successful attack against Yoriaki and Toki Yorizumi at Ōga Castle, overcoming the defenders and roundly defeating the Oda and Asakura forces supporting the Toki.  This event was known as the Battle of Kanōguchi.  Thereafter, Dōsan had his daughter wed Nobuhide’s eldest son, Oda Nobunaga, in a political marriage to enable peace with the Oda.  However, in 1555, Dōsan’s son, Saitō Yoshitatsu, raised arms against his father, and, in 1556, Dōsan was killed in battle against the rebel army at the Battle of Nagaragawa.  In 1561, Yoshitatsu’s son, Saitō Tatsuoki, succeeded his father. Over the ensuing five-year period, Oda Nobunaga invaded Mino and, in 1567, he changed the name of Inabayama Castle to Gifu Castle.  In 1568, Nobunaga marched upon Kyōto and installed Ashikaga Yoshiaki as the next shōgun who was subservient to Nobunaga.

Owari Province became the home base of the Shiba clan after their alienation from the Asakura of Echizen.  After losing a battle against the Asakura in a failed effort to recover their territory in Echizen, the Shiba further lost in politically motivated conflicts in the capital of Kyōto, relegating them to the role of a puppet administration under the control of the Oda who served as deputy military governors of Owari.  In 1554, Shiba Yoshimune committed suicide after being embroiled in power struggles among the Oda, ending the tenure of the Shiba as military governors.  Thereafter, the Oda ruled Owari.  While serving as deputy military governors, the Oda clan was divided between two branches.  Oda Nobunaga came from the branch of a commoner family lineage with the status of a district official.  After a prolonged power struggle between the two branches, Nobunaga ultimately prevailed and became the lord of Owari.  After defeating Imagawa Yoshimoto, the powerful daimyō from neighboring Suruga Province, at the Battle of Okehazama, Nobunaga allied himself with Matsudaira Motoyasu (later known as Tokugawa Ieyasu) who had recovered the former domain of the Matsudaira in Mikawa after being liberated from the Imagawa after the death of Yoshimoto. Together, Nobunaga and Motoyasu turned their focus to attacks on Mino.  After a five-year period, Nobunaga captured Mino from Saitō Tatsuoki, changed the name of Inabayama Castle to Gifu Castle, and made it his new base of operations from which to expand his hegemony.

Imagawa Ujichika of Suruga wrested control of Tōtōmi Province away from the Shiba clan, and, in 1526, promulgated a set of provincial laws known as the Imagawa kana mokuroku to formalize his authority over the territory.  In the era of Imagawa Yoshimoto, the Imagawa further gained control of the Matsudaira domain in Mikawa Province.  In 1554, Yoshimoto entered into a three-way alliance with the Takeda of Kai and the Hōjō of Sagami (known as the Zentoku Temple Alliance).  Yoshimoto reinforced efforts to expand to the west, extending his influence into a portion of Owari.  In 1560, Yoshimoto died in an attack by Oda Nobunaga at the Battle of Okehazama, and although he was succeeded by Imagawa Ujizane, the clan weakened and was vanquished in the Suruga Invasion by the Tokugawa and the Takeda.

In the era of Matsudaira Kiyoyasu, the Matsudaira of Mikawa embarked on expanding their domain, however, in 1535, Kiyoyasu was slayed by one of his retainers during a deployment in an incident known as the Collapse at Moriyama (Moriyama kuzure), causing a sudden change in circumstances.  Without the support of the Imagawa clan of Suruga, the Matsudaira faltered.  Matsudaira Motoyasu (later known as Tokugawa Ieyasu) had been transferred to the Imagawa as a hostage in his youth, and after his coming-of-age, participated in the vanguard of Imagawa forces at the onset of the Battle of Okehazama.  After the battle, he took advantage of the instability within the Imagawa domain and, in 1565, pacified Mikawa, changed his name to Tokugawa Ieyasu, became independent of the Imagawa, and forged an alliance with the Oda.  Based on a secret understanding with the Takeda, both clans encroached on the Imagawa territory in Suruga from the east and west.  In the Invasion of Suruga, the Imagawa collapsed in 1569. Thereafter, a westward advance launched by Takeda Shingen resulted in the occupation of portions of the Tokugawa territory in Mikawa.  In 1573, at the Battle of Mikata-ga-hara, allied forces of the Tokugawa and Oda suffered a major defeat.  Ieyasu confronted a precarious situation with the loss of Mikawa, but the death by illness of Takeda Shingen abruptly ended the westward advance and their lives were spared.

In 1575, at the Battle of Nagashino, the allied forces of the Oda and Tokugawa deployed forces in rows with arquebuses to defeat the Takeda army, and, in 1582, for meritorious results in the Kōshin Expedition, Nobunaga awarded the Tokugawa the former Takeda territory of Tōtōmi and Suruga.  Moreover, the same year, following the death of Nobunaga in the coup d’état known as the Honnō Temple Incident, Ieyasu invaded the Oda territory of Kōshin and imposed control.

In 1590, after Toyotomi Hideyoshi garnered control of the country, Ieyasu was compelled to relocate to the Kantō, so he established his base in Edo in Musashi Province.  Following the demise of Hideyoshi, Ieyasu prevailed in the Battle of Sekigahara and formed the Edo bakufu based in the Kantō.

The Kinai Region

In the early part of the Sengoku period, the Ashikaga shōgun family engaged in struggle against the Hosokawa who served as the deputy shōgun.  Local lords in Yamashiro Province formed bands of resistance that further enflamed the conflict.  Meanwhile, clans from outlying areas such as the Ōuchi used the Ashikaga clan as a reason to intervene in the conflict among central authorities.  After internal power struggles weakened the Hosokawa clan, the Rokkaku from Ōmi intervened on the basis of supporting the Ashikaga.  In Ōmi, a branch of the Sasaki clan in northern Ōmi known as the Kyōgoku fought against the Rokkaku of southern Ōmi for control of the province, but the Kyōgoku were usurped by the local Azai clan who were their retainers.  Thereafter, battles persisted between the Azai and the Rokkaku.

In many provinces, military governors appointed by the Muromachi bakufu evolved into sengoku daimyō.  These daimyō served for the benefit of local lords so in many cases their position was vulnerable.  The Hatakeyama of Kawachi, the Yamana of Tajima, the Isshiki of Tango, and the Takeda of Wakasa were all at risk of losing their provinces to other influential clans in their environs or to rebellion by their own retainers, narrowly surviving the turbulence of the period.

In Iga Province, influential families led by those with ninja warriors governed through a feudal form of a parliamentary system, while northern portions were loosely governed by the Rokkaku and southern portions by the Kitabatake.

In Kii Province, members of the Negoro Temple, the three major shrines of Kumano, and monks associated with the temples in elevated flatlands known as Kōyasan were powerful while the Hatakeyama exercised limited authority in their role as military governors.  Local samurai from Kii formed bands such as the Negoro Group (Negoro-shū) and the Saika Group (Saika-shū) and self-governed their territories under the banner of religion.

In Ise and Shima provinces, the Kitabatake clan carried influence from the time of the Nanbokuchō period (1336 to 1392) as representatives of the central authorities, and in the era of Kitabatake Harutomo, evolved into sengoku daimyō.

The power struggle between the ruling Ashikaga clan and the Hosokawa swept-up numerous other influential families in the environs of the capital, including the Rokkaku, the Akamatsu, the Uragami, the Hatakeyama, and the Tsutsui; however, this escalated into a full-scale conflict after the Miyoshi seized political power.  Beginning with their home province of Awa in Shikoku, the Miyoshi acquired control of Sanuki, Awaji, Settsu, Izumi, Kawachi, Yamashiro, Tanba, and Yamato through their own devices, earnestly governing each province.  Nevertheless, the Miyoshi did not possess full control of each province.  Following the death of Miyoshi Nagayoshi, the clan became unstable and was later pacified by the army of Oda Nobunaga that marched upon Kyōto in 1568.

The Sanyō and Sanin Region

In the early part of the Sengoku period, Ōuchi Yoshioki of Suo Province engaged in multiple battles against Amago Tsunehisa of Izumo Province without a decisive outcome.  From coastal areas on the Sea of Japan, the Ōuchi expanded their influence to seven provinces in addition to possessing exclusive rights to the tally trade with the Ming dynasty in China.  Yoshioki marched to Kyōto to honor the shōgun with the support of daimyō based in the environs of the capital.  Initially serving as a deputy military governor, Tsunehisa captured Gassantoda Castle and banished the military governor, establishing his presence in Izumo in the Sanin Region.

Local families of influence in Aki Province located between the powerful Ōuchi and Amago domains banded together for their mutual defense.  Mōri Motonari arose out of this situation to become the leader of this band and evolve into a sengoku daimyō.  Motonari initially achieved a diplomatic balance between the Ōuchi and the Amago, but later betrayed the Amago and aligned with the Ōuchi, whereupon Amago Haruhisa led an army toward Yoshida-Kōriyama Castle.  Motonari called upon Ōuchi Yoshitaka for reinforcements, and after the arrival of these forces, attacked and defeated the Amago at the Battle of Yoshida-Kōriyama Castle.

Ōuchi Yoshitaka died in a revolt led by a retainer, Sue Harukata, in an event known as the Tainei Temple Incident (Taineiji no hen).  Amago Haruhisa, a military governor in control of eight provinces, stood as a rival to the Sue clan who backed Ōuchi Yoshinaga as their puppet.  Late in 1555, Harukata was killed by forces under Mōri Motonari at the Battle of Itsukushima.  The Mōri then attacked and decimated the Ōuchi clan.  The sudden death of Haruhisa in Izumo led to a weakening of the clan, inviting an attack by the Mōri.  The Amago took refuge in the impregnable Gassantoda Castle.  The Mōri proceeded to block the provisioning of the castle, and with the dwindling of their supplies over time, the defenders surrendered in an engagement known as the Battle of Gassantoda Castle.  This enabled the formation of hegemony by the Mōri in the western provinces.

Motonari’s grandson, Mōri Terumoto, offered protection to Ashikaga Yoshiaki after the latter was deposed and banished by Oda Nobunaga from the capital of Kyōto.  The Mōri became the most significant source of resistance to the westward invasion by Oda as a key component of Nobunaga’s aim to become supreme leader of the entire country.  Yamanaka Yukimori raised arms on multiple occasions in an effort to resuscitate the Amago clan, but was forced to retreat.  An Oda army led by Hashiba Hideyoshi (later known as Toyotomi Hideyoshi) led the western campaign, toppling Miki, Tottori, and Takamatsu castles along the way.

Immediately after receiving news of the Honnō Temple Incident, a dramatic coup d’état orchestrated by Akechi Mitsuhide that resulted in the untimely death of Nobunaga, Hideyoshi reconciled with Terumoto and hurriedly retreated from the western region to confront the aggressors near Kyōto.  Having been spared a continuing onslaught by the Oda, Terumoto later came under the command of the Toyotomi, participating in campaigns in Shikoku and Kyūshū, as well as the Odawara Expedition.  Terumoto then became one of the five elders in the Toyotomi administration.  In 1589, Terumoto utilized profits from maritime trade to commence the construction of Hiroshima Castle.  During the Edo period, the Hiroshima han presided over a fiefdom of 426,000 koku in the community surrounding the castle in Aki Province.  After the death of Toyotomi Hideyoshi, a confrontation between Tokugawa Ieyasu and Ishida Mitsunari led to the Battle of Sekigahara.  Terumoto served as the lead commander for the western army, and, after the battle, served as the governor of Suō and Nagato provinces with a production yield of 369,000 koku.

Other notable sengoku daimyō included Uragami Muramune and Ukita Naoie, both of Bizen Province.  Muramune served as a senior retainer of the Akamatsu clan of Harima, but, after the demise of Akamatsu Masanori, seized control of Harima, Bizen, and Mimasaka provinces.  Muramune marched to Kyōto in support of Hosokawa Takakuni when Takakuni faced dire circumstances, but died in battle against the Miyoshi.  In the era of Uragami Munekage, the clan collapsed after an insurrection by Ukita Naoie.  Having taken control of Bizen, Naoie appeared to read the tides of change, choosing to surrender to Hashiba Hideyoshi after the latter entered Himeji Castle in Harima and transferring his eldest son, Ukita Hideie, to Hideyoshi as a hostage.  Hideie served in the vanguard for the western army at the Battle of Sekigahara, but, after the conflict, was exiled to Hachijō island for having served as a key bushō of the defeated western forces.  Thereafter, the Ukita clan was vanquished.

Shikoku Island

Awa and Sanuki provinces in eastern Shikoku were close to the Kinki region, and served as a base of power for the Hosokawa clan, drawing the families in these provinces into political conflicts unfolding in Kinki.  Owing to the absence of capable enemies in their surroundings, the landlords rarely changed until the quest of the Chōsokabe clan from Tosa Province to unify the entire island of Shikoku.

The Hosokawa ruled Awa Province.  Later, the Miyoshi from the Muya area in northest Awa succeeded the Hosokawa, but the Hosokawa clan itself retained a presence in Awa until the Edo period.  In the Sengoku period, Shōzui Castle served as the base for the governance of Awa.  Sanuki Provinces was ruled by the Yasutomi clan of eastern Sanuki.  Later, the Sogō clan of the Kita district (associated with the Ueda clan) received Miyoshi Nagamasa (Sogō Kazumasa) and expanded their influence while serving as a magistrate of the Miyoshi, and quickly took over eastern Sanuki.  The Kagawa clan who served as deputy military governors in western Sanuki joined forces with the Mōri to initially resist the Miyoshi, but after the Battle of Zentsū Temple, came under the command of the Miyoshi.  Once the Miyoshi weakened, the Kagawa yielded to the Oda clan.

In Iyo Province, the Kōno governed central Iyo, the Iyo-Utsunomiya occupied the area around Ōzu, and the Saionji clan held influence in southern Iyo.  Geographically, the province featured numerous long and narrow mountainous districts.  Close proximity to the Chūgoku region and to Kyūshū invited frequent intervention by other clans including the Mōri and the Ōtomo, so none of the local families had sufficient resources to unify Iyo under its control or to invade other provinces.  However, the locals mustered stiff resistance to invasions by the Chōsokabe clan based in neighboring Tosa Province.

Although the Hosokawa clan served as the military governors of Tosa Province, seven influential families competed for control in central Tosa.  Among them, the Tosa-Ichijō clan who had evacuated to the Hata District was revered as the leading power.  The Ichijō wielded three times the power of the other families and engaged in the politics of Tosa.  Later, Chōsokabe Kunichika and Chōsokabe Motochika benefited from the support of the Ichijō, but later banished the Ichijō along with the other families in the course of unifying the province.  Following the pacification of Tosa, after a ten-year period, the Chōsokabe unified all of Shikoku island in 1585.  The Hosokawa continued to govern Awaji Province.  After the invasion of Shikoku by Toyotomi Hideyoshi, the Chōsokabe were cornered back to Tosa.  Thereafter, Hideyoshi assigned trusted commanders to Shikoku, including Hachisuka Iemasa to Awa, Sengoku Hidehisa to Sanuki, and Kobayakawa Takakage to Iyo.

Kyūshū Island

The military families in Kyūshū were associated with the Heike lineage, so did not receive much support from Minamoto Yoritomo, the first supreme shōgun of the Kamakura bakufu.  To exert control in Kyūshū, Yoritomo appointed local families such as the Shōni, the Ōtomo, and the Shimazu as military governors and official representatives of the bakufu despite these families being relatively unknown in the Kantō.  In the Kamakura period (1185 to 1333), the Shōni governed Chikuzen, Hizen and Buzen provinces, the Ōtomo governed Chikugo, Higo, and Bungo provinces, and the Shimazu governed Satsuma, Ōsumi, and Hyūga provinces.  Military families who were aligned with the Heike lineage, including the Matsuura, the Akizuki, the Kamachi, and the Kikuchi became firmly rooted in their role as officials under the governors.  At the outset of the Sengoku period, the Shōni, the Ōtomo, and the Shimazu aimed to protect their interests, while the military families serving under them strived to become independent.  These opposing objectives gave rise to clashes between the governors and the families serving them.

In the latter part of the Muromachi period, opposition by the Shōni to the local military representatives of the Muromachi bakufu in Kyūshū led to loss of power by the clan, while clans based in Chikuzen and Buzen such as the Munakata and the Asō were influenced by the Ōuchi from the Chūgoku region.  The Shōni led soldiers from Hizen and Tajima provinces invaded Chikuzen on multiple occasions in an effort to expel the Ōuchi, but, instead, were usurped by the Ryūzōji who supported the Ōuchi.  Once the Sue clan ousted the Ōuchi, Hizen became independent, while Chikuzen and Buzen were subject to intervention by the Ōtomo clan.  Relatives of the Mōri from the Chūgoku region eliminated the Sue and established a presence in both provinces, leading to clashes between the Mōri and Ōtomo in northern Chikuzen.

Based in Bungo, the Ōtomo expanded their influence in Chikugo where fifteen families led by the Munakata of Southern Chikugo held sway, and in Higo where the Aso and Sagara clans exercised influence.  After the Sue defeated the Ōuchi, the Ōtomo supported them and garnered control of Buzen and Chikuzen.  Meanwhile, Ōtomo Yoshishige tolerated the Christian religion, enabling marine trade with foreigners to flourish.  However, the Ōtomo fell into a steep decline following a major defeat against the Shimazu at the Battle of Mimikawa and successive defections by retainers and families formerly under their control.  This provided an opening for the Ryūzōji who quickly expanded their influence after rebelling against the Shōni.  In the era of Ryūzōji Takanobu, the clan nearly reached parity with the Ōtomo and the Shimazu, but rapidly declined following the death of Takanobu at the Battle of Okitanawate against allied forces of the Shimazu and the Arima.  Takanobu was succeeded by a senior retainer named Nabeshima Naoshige.

In the early part of the Sengoku peirod, the Shimazu clan endured internal conflict, and Shimazu Takahisa (the son of Shimazu Tadayoshi), a cadet family of the clan, took over the main branch.  The Shimazu fought incessantly against other influential families such as the Kedōin, the Hishikari, and the Kimotsuki.  Thereafter, the Shimazu unified Satsuma and Ōsumi under the command of Shimazu Yoshihisa (the son of Takahisa).  After the Battle of Kizakibaru, the Shimazu suppressed the Itō clan and achieved a resounding victory against Ōtomo Yoshishige at the Battle of Mimikawa, while pacifying Satsuma, Ōsumi, and Hyūga provinces.  This led to a conflict for the control of all of Kyūshū, and with only Chikuzen and Buzen remaining, the Toyotomi army led by Hideyoshi intervened and caused surrender.

Military affairs

Although clans were not continuously in combat during the Sengoku period, military force was often relied upon as a means to resolve disputes between rivals, and clans turned their attention to armaments for this purpose, including the organization, maintenance, and improvement of their state of military preparedness.  Beginning with the sengoku daimyō and clans of local influence, this perspective also extended to religious groups and autonomous bodies.  The religious groups maintained ranks of monk-soldiers, and constructed and operated their temples to serve as bases for war.  Meanwhile, autonomous bodies of local citizens constructed towers, fences, and moats for defensive purposes, engaging wandering samurai to serve as mercenaries on their behalf.  These organizations devised unique military tactics such as the emergence of secretive ninja groups of fighters.  Even a subset of nobles partook in military activities that were not solely for self-defense, such that many classes of society dedicated efforts to resisting threats of force.

Battles

Battles during the Sengoku period came in a wide variety of forms.  These ranged from low-intensity shows of strength and small skirmishes between individual daimyō to armed conflicts between armies over the control of territory, assaults on castles, open-field battles, conflicts that unfolded over a successive period of battles such as the Battle of Kawanakajima, expeditions to non-contiguous regions such as the westward advance led by Hashiba Hideyoshi, and, soon after the end of the Sengoku period, foreign expeditions to the Korean Peninsula and, finally, epic showdowns symbolized by the Battle of Sekigahara whereby allied forces squared-off against one another in a decisive battle for national hegemony.

In the context of all of the military conflicts, the majority involved back-and-forth skirmishes or disputes unfolding in the border areas between unfriendly neighboring forces who engaged in an ongoing struggle for territory and influence.  This tension gave rise not only to the use of force against enemy soldiers, but also the antagonism of neighbors, including such acts as arson, the destruction of rice and wheat crops, and, in certain cases, these events escalated into full-scale battles between opposing clans.  Frequently, individual bushō would introduce themselves and then engage in a decisive one-on-one duel.  The victors would carry home the heads of the defeated, and be recognized for their achievements.

In 1543, Tanegashima Tokitaka purchased a cache of arquebuses from Portuguese traders who landed on Tanegashima in Ōsumi Province.  The introduction of the arquebus to Japan marked a dramatic revolution in battle tactics.  Divisions of arquebus-wielding soldiers augmented traditional mounted soldiers as well as foot soldiers bearing long and short swords, spears, and the bow and arrow.  In 1575, at the Battle of Nagashino, Oda Nobunaga made effective use of a large number of infantry for the synchronized fire of arquebuses that decimated the mounted soldiers of Takeda Katsuyori.  In 1584, at the Battle of Okitanawa, the allied forces of Shimazu Iehisa and Arima Harunobu defeated a superior number of forces under Ryūzōji Takanobu with a lightning assault led by the infantry resulting in the death in battle of Takanobu.

Military tactics and the choices of weapons deployed in battle differed among individual daimyō and by region.  Oda Nobunaga actively deployed large cannons in battles for unification, while Toyotomi Hideyoshi chose not to make significant use of cannons.  Many of Nobunaga’s battles occurred in the Kinai Region which exhibited higher levels of innovation than other locales, whereas Hideyoshi frequently deployed to more distant provinces, lessening the need and practicality of deploying cannons.  In 1593, after deploying in Nagoya in Hizen Province, a daimyō named Nanbu Nobunao from Mutsu Province was awestruck by the armaments of the Toyotomi army, highlighting the regional differences in military capability existing in that period.

Castles and Construction

Castles primarily constructed of stone walls, stone foundations, tile roofing, and plastered interior walls made their advent in the Azuchi-Momoyama period, exemplified by Gifu and Azuchi castles, under the direction of Oda Nobunaga.  In the Sengoku period, the majority of castles and fortresses were made of earthen construction through excavation and shaping of the land.  Stone was used only on limited portions.  In the latter part of the fifteenth century, stone walls up to four meters high were constructed.  Mountain fortresses generally served as defensive positions while citadels situated around the base of mountains served as residences.  This strategy to separate the fortress from the primary residence first became common in the Muromachi period.  Excavations at sites such as Odani, Kanonji, and Okishio castles in mountain-top locations also revealed stone foundations and evidence of living quarters such as ceramics and utensils.  In the latter part of the Sengoku period, military governors (shugo daimyō) and sengoku daimyō maintained living quarters not only in residences in the foothills, but also in the mountain fortresses.

The sengoku daimyō exhibited individualized construction skills and capabilities, reflecting their personal military doctrines.  Castles held by the Kai-Takeda clan featured defensive perimeters to enable firing of arquebuses or bow and arrow in counterattacks, while castles held by the Gohōjō in the Kantō and castles in northern Kyūshū included ascending trenches on slopes to impede the advance of enemy forces.  Meanwhile, the proliferation of arquebuses in the Kinai Region led to the construction of watchtowers and turrets as a component of many castle fortifications.  Castle design reflected variations in the threat landscape of each region.  Beginning in the late sixteenth century, a transition occurred from a reliance on mountain-top castles serving as military bases to the construction of castles on plains or along waterways in closer proximity to the commercial and economic activities occurring in castle towns.

Economics and Society 

Based on production levels, medieval society on the Japanese archipelago can be divided into three regions: a region comprised of provinces near Kinai (most developed), the central regions (developing), and remote regions (undeveloped).  The practice of growing rice and wheat crops on an alternating schedule spread throughout the Kinai Region and western provinces, and, in Kinai, some peasants grew three crops, while farming in eastern Japan remained mostly limited to one crop.  Unlike rice, wheat was exempt from taxes so the peasants could keep their entire crop, making the practice of growing two crops important to their survival.  In addition to the practice of growing two crops, production increased significantly in the medieval period owning to improvements in irrigation and land management.  Meanwhile, the Sengoku period witnessed an extended period of cooling climate, causing a loss of crop production.  Particularly in the eastern provinces, starvation became a common occurrence, giving rise to peasant revolts that contributed to the eventual collapse of the Muromachi bakufu.  To save themselves, citizens of one province began to plunder the food and wealth of other provinces, fueling the outbreak of conflicts during the period.

Frequent battles in the Sengoku period fostered the flow of people and goods, increasing the value of currency as standard unit of value.  In the early part of the Sengoku period, authorized trade with the Ming dynasty known as the tally trade, along with smuggling and trade with other foreign countries such as Spain and Portugal enabled the import of a variety of goods including a large quantity of copper coins from China, providing the means for a currency-based economy in Japan.  Visitors from Europe fostered an active trade in gold and silver, as represented by the infamous Iwami Silver Mine in Iwami Province, which at its peak produced almost one-third of the world’s silver.  These developments raised the importance of gold and silver mines to the overall economy.  New metallurgical processes such as cupellation and the use of hearths were devised to improve the quality of gold and silver.  Fortresses were built for the primary purposes of protecting gold and silver mines, while conflicts arose between sengoku daimyō related to mining rights.

In 1568, after Oda Nobunaga marched upon the capital of Kyōto, he authorized the formation of free markets known as rakuichi-rakuza in lieu of prior associations of merchants and artisans based on the payment of fees to temples, shrines, and other landowners for exclusive trading rights or stock-based cartels.  Thereafter, the Toyotomi administration continued support for the free market model in areas under the their jurisdiction as well as in the provinces controlled by daimyō across the country.  Accompanying the growth of commercial activity, Hideyoshi introduced a common currency in place of those currencies recognized only at the provincial level.

Meanwhile, in rural districts, independently operated manors known as shōen were subject to seizure by sengoku daimyō and local landowners, resulting in the dismemberment of the shōen system.  Certain elements including the system for calculating levies and the multi-layered ownership structure for land persisted, but gradually these were replaced by systems introduced by daimyō to equalize assessments such as annual land taxes.  The principle of individual land ownership took root, while land lending became common along with the payment of rice taxes to landowners and cost-bearing by peasants.  The sengoku daimyō promoted large-scale development of arable lands along with irrigation projects.  Construction methods developed in the building of castles were leveraged for agricultural purposes.  During the Keichō era (1596 to 1615), the crop land across the country increased from 1 million hectares to 1.6 million hectares.  In addition to rice, other crops grown including tea in Yamashiro and Yamato provinces as well as citrus products in Kii Province.  Cotton production also expanded during this period.

The harbor towns of Sakai and Hakata flourished as commercial centers.  Traders often relied upon waterways to move goods and people between hubs, and a transport network began to form between Japan and southeast Asia.  Sakai witnessed particularly remarkable growth, led by a deliberative body of town elders who relied upon a consensus-based system to engage in self-governance.  A moat encircled the entire town, while wayfarers and mercenaries served as hired hands.  The town firmly opposed attempts by sengoku daimyō to govern their affairs.  Meanwhile, the capital of Kyōto, along with Yamaguchi, Obama, and Shingawa-minato served as notable intermediate centers of commerce.

Military tactics evolved from individual tactics to group tactics, increasing demands for weapons and armor.  This caused the blacksmiths to change their emphasis to the production of large quantities of average-grade material instead of producing high-grade individual weapons.  The proliferation of firing weapons such as arquebuses increased the importance of logistics to supply consumable items such as gun-powder whereas formerly most armaments could have been maintained in advance for use only upon the outbreak of a conflict.  These developments gave rise to a class of merchants who primarily focused on armaments and supplies for the ongoing battles.

Peasant samurai

Rank and file samurai known as bushi who engaged opposing forces on the battlefield were also known to frequently engage in plundering of people and possessions after these conflicts.  This included setting fire to homes, slashing crops, and abducting and enslaving peasants and townspeople.  Peasants who were conscripted as foot soldiers were not compensated without merit, and it was not an easy matter to kill a well-known bushō.  To maintain morale, daimyō would implictly permit or even encourage plundering by their soldiers.  Uesugi Kenshin (formerly Nagao Kagetora) actively planned for deployments to other provinces, and without regard to whether these were for short or long campaigns, did so in the winter season.  This may have been to create opportunities for soldiers to provide for themselves in other locales while avoiding hardship in his home province of Echigo.

There are records of plunder and enslavement in many locales, including the sale of captured people to overseas destinations through the intermediation of Christian missionaries. These circumstances led Toyotomi Hideyoshi, in 1587, to issue an order for the expulsion of all Jesuit missionaries and to ban the practice of the Christian religion.  Outside of the plunder occurring in the wake of battles, the slashing of crops also occurred between provincial neighbors as part of a strategy to reduce the economic clout of rival daimyō.

Culture

Culture during the early part of the Sengoku period featured influences from Kitayama and Higashiyama culture, in addition to the influence of Zen Buddhism.  The usurpation of those in positions of greater authority known as gekokujō which served as one of the defining characteristics of the Sengoku period also affected the culture, gradually laying the groundwork for the splendor of the Momoyama culture.

In particular, the attainment of a tea ceremony introduced by the tea master named Sen-no-Rikyū that encompassed a sense of aestheticism known as wabi-sabi inspired by Zen thought and a golden tea house of extraordinary beauty as conceived by Toyotomi Hideyoshi exerts a notable influence on Japanese culture overall even to the present time.

Artists during the Sengoku period included, among others, Sesshū, Sesson, Tosa Mitsunobu of the Tosa faction, Kanō Motonobu of the Kanō faction, and Hasegawa Tōhaku.  From the Muromachi period, certain bushō acquired an interest in the cultural arts.  Toki Yoriaki and Takeda Nobukado produced works recognized for their artistic value.

During this extended period of war and conflict, the Emperor’s family and nobles served as pillars of cultural life, compelled to understand the value of cultural inheritance and making cultural innovations themselves.  The military families of cultural figures such as Tō Tsuneyori and Hosokawa Yūsai also demonstrated an affinity for cultural affairs, extending to a respect for the time-honored customs, ceremonies, dress, practices, norms, titles, systems, and laws governing the Emperor, nobles, and military families.  Certain figures moved to remote locations to escape the conflict engulfing other regions.  As an example, a school of painting known as nanga had its inception in the remote province of Tosa on Shikoku island.

As with respect to the Konoe family which preserved its status in noble society through marriages to the Ashikaga shōgun family, other families endeavored to preserve their social status by mediating between the Imperial court and local daimyō and bushi.  For some, however, the bushi usurped their special privileges, causing them to become destitute and isolated in remote areas without personal connections, resulting ultimately in their demise.  In 1519, at the Battle of Koshimizu Castle in the Muko district of Settsu Province, the diaries of Konoe Hisamichi and a noble named Washi-no-o Takayasu highlight their different perspectives.  Hisamichi obtained updates regarding the battle from a variety of individuals of differing social ranks, including bushō, their retainers, and monks.  In contrast, Takayasu relied solely on rumors from members of the noble class, which struck him with fear.  Members of noble families had minimal contact with members of other classes such as bushi, and eventually disappeared from history.  As an illustration, the Washi-no-o clan was extinguished in the era of Takayasu, but finally made a revival in the early party of the Edo period.

Well-known military families as well as families of newly found influence contributed to cultural progress.  In certain respects, the cultivation of arts enabled families to gain prestige, but the pursuit of cultural interests also provided a source of peace and calm in the midst of an otherwise tumultuous and violent period.  On multiple occasions, Ōuchi Yoshitaka of Suō Province invited royal guests from Kyōto to visit him in Yamaguchi and endeavored to emulate the culture of the capital in Yamaguchi.

Religion

The most prominent religious groups included the Nichiren sect (a branch of Mahāyāna Buddhism) and the Jōdo shinshū sect (a branch known as the True Pure Land school of Buddhism).  A prevalence of pessimism in society and need for redemption drew followers to religion, including a strong connection to the desire for an afterlife.  Meanwhile, the Catholic religion proslytized by Jesuit missionnaries from Spain and Portugal also made limited inroads in certain locales.

From the introduction of Buddhism to Japan in the Asuka period (538 to 710), there were fervent believers in Shintō and Buddhist gods based on a fusion of the indigenous Shintō religion and domestic adaptations of Buddhism.  In the Sengoku period, concepts of Divine providence spread among bushō, along with a recognition of being subject to the will of Heaven.  This gave rise to a unitary structure of religion in Japan within a common framework of polytheistic beliefs drawing from Buddhism, Confucianism, and Shintoism.  These beliefs were held among the military class as well as commoners, permeating deeply into Japanese society.

For a Japanese version of the Sengoku period, go to the Japanese Wikipedia site.