Amago Tsunehisa served as shugodai, or deputy military governor, of Izumo Province.  He was known as the taishu, or governor-general, for eleven provinces in western Japan.  Tsunehisa was the eldest son of Amago Kiyosada, the former deputy military governor of Izumo.  As a youth, he was called Matashirō.  Tsunehisa exemplified the phenomenon during the Sengoku period of gekokujō by which persons of lower rank usurped the power of those above them.  He was known along with Mōri Motonari and Ukita Naoie as a brilliant strategist among lords in the western provinces.  Together with Motonari and Naoie, Tsunehisa is referred to as one of the Three Strategists of Chūgoku.

In 1474, Tsunehisa was sent as a hostage to the residence of Kyōgoku Masatsune in Kyōto, lord of Kiyosada and military governor of Izumo, Hida, Oki, and Ōmi.  He resided in Kyōto for the next five years during which he had his coming-of-age ceremony.  He received one of the characters from Masatsune’s name and became known as Tsunehisa.  He then returned to Izumo and, in 1478, succeeded his father as head of the clan.

Succession as head of the clan

Although Tsunehisa initially supported the Kyōgoku, he gradually became closer to the kokujinshū, or class of provincial landowners.  Disregarding orders from the Muromachi bakufu, he seized from Masatsune the districts for temples and shrines, and established an independent base of power by refusing to levy extraordinary taxes at Mihonoseki to support these districts.  However, Tsunehisa’s expansion of influence reached limits owing to confrontation with the Enya clan from the western portion of Izumo.  His actions further triggered opposition from the bakufu, the military governor, and the kokujinshū.  In 1484, opponents laid siege to his castle and stripped him of his role as deputy military governor, but he retained limited influence in Izumo.  In 1488, Tsunehisa attacked the Mizawa, kokujin in Izumo, and compelled their surrender, serving as evidence of a continuing role in the province at this time.

In 1500, Tsunehisa completely restored his role as deputy military governor based on reconciliation with Masatsune.  This occurred in the wake of Masatsune’s defeat after a prolonged internal struggle for control of the Kyōgoku clan in Ōmi Province, an event known as the Kyōgoku Disturbance (Kyōgoku sōran).  After the death of Masatsune, Tsunehisa constructed the Kizuki no Ōyashiro, promoted marital relations with the Shinji clan to shore-up resistance to the Enya, and began to secure his position as the leader of Izumo Province.  Masatsune assigned leadership of the clan to his grandson, Kyōgoku Kichidōjimaru, and died in 1508.  Tsunehisa was entrusted to serve as his guardian, but Kichidōjimaru soon disappeared from the scene while Tsunehisa became the de facto lord of Izumo Province. Nevertheless, resistance to Tsunehisa continued within Izumo, and Tsunehisa did not obtain full control of the province until over a decade later in the Daiei era (1521-27).

The expanding influence of the Amago clan

In 1511, Ōuchi Yoshioki, head of the powerful Ōuchi clan which had wielded power in the Chūgoku Region for generations, marched upon Kyōto.  Tsunehisa abided by this action, and participated in the Battle of Funaokayama.  In 1512, Tsunehisa supported a rebellion by Koshi Tamenobu, lord of Ōbayama Castle in Bingo Province against the Ōuchi clan.  At this time, his second son, Amago Kunihisa received one of the characters in his name from Hosokawa Takakuni and his third son, Enya Okihisa, received one of the characters in his name from Ōuchi Yoshioki reflecting Tsunehisa’s effort to build closer ties with these families.

In 1513, Tsunehisa had his younger brother, Amago Hisayuki, attack Nanjō Sōshō in Hōki Province.  Meanwhile, he directed his eldest son, Amago Masahisa, to attack Sakurai Sōteki in Ayō Castle in response to a rebellion, but Masahisa was felled by an arrow during the ensuing battle.

In 1517, Tsunehisa joined with the Yamana clan, the prior military governor of Iwami Province, to attack castles allied with the Ōuchi in Iwami Province.  This occurred after the Yamana refused to have Ōuchi Yoshioki serve as the military governor of Iwami.  Nevertheless, these were limited to skirmishes and not an invasion of the Ōuchi domain.  In 1518, Tsunehisa cooperated with the Shinmi clan who had influence in the northern portion of Bitchū Province to attack the Mimura clan.  In 1520, Tsunehisa finally secured control of west Izumo, but this led to confrontation with kokujin having landholdings on the provincial border, including the Yamauchi clan of Bingo Province and the Shishido of Aki Province. In particular, the influence of the Yamauchi clan in Izumo could not be underestimated. The advance into Bingo and Aki therefore became essential to securing control of Izumo and led to military clashes with the Ōuchi who held interests in the same territories.

In 1521, the Amago invaded Iwami Province and extended into Aki.  In 1523, a senior retainer of Tsunehisa named Kamei Hidetsuna ordered the Mōri, kokujin in Aki Province, to attack the economic center of the Ōuchi in Aki at Kagamiyama Castle.  At this time, the Mōri in Aki were led by Mōri Kōmatsumaru, a nine-year-old child under the guardianship of his uncle, Mōri Motonari.  Motonari initiated an attack with 4,000 soldiers led by Kikkawa Kunitsune in the Battle of Kagamiyama Castle, and launched a plot against the defenders by convincing Kurata Naonobu to betray his family.  Naonobu was the uncle of Kurata Fusanobu, lord of Kagamiyama Castle.  Following the betrayal, Fusanobu killed himself and the castle fell to the Amago. Afterwards, Naonobu was also compelled to take his own life.

In 1524, Tsunehisa led an invasion of the western portion of Hōki Province, and defeated Nanjō Sōshō, and then routed Yamana Sumiyuki, the military governor of Hōki, gaining control of the area in a period of days.  The defeated kokujin in Hōki fled to Inaba and Tajima provinces, while Nanjō Sōshō requested support from the Yamana clan of Tajima. Meanwhile, the Takeda and Tomoda of Aki, allies of the Amago, lost to the Ōuchi.  In 1525, following an internal struggle against Aiō Mototsuna, a younger brother of a different mother, Mōri Motonari broke with the Amago in favor of the Ōuchi. This triggered a change in the balance of power among the kokujin in Aki aligned with the Amago.   Intervention in the succession struggle by Kamei Hidetsuna, a retainer of the Amago, is noted as a key reason for the estrangement of the Mōri, but the strong intentions of Tsunehisa further played a role.

In 1526, the Yamana clan who served as the military governor in Hōki and Bingo revealed their opposition, leaving the Amago in a vulnerable position surrounded by the Ōuchi and the Yamana.  In 1527, Tsunehisa himself led forces into Bingo Province, losing to Sue Okifusa in the Battle of Hosozawasan, whereupon a majority of the allied kokujin in Bingo switched their allegiance to the Ōuchi.

Rebellion by Enya Okihisa

In 1528, Tsunehisa entered Bingo again and toppled Shitomiyama Castle held by the Tagayama clan, but the Takahashi clan, an ally in Iwami Province, suffered defeat by the Mōri and Wachi clans.

In 1530, an internal struggle for control erupted between Tsunehisa and Enya Okihisa, the third son in the family.  At this time, Okihisa drew support from a wide range of actors, including, among others, the Kizuki no Ōyashiro, the Engaku Temple, the Mizawa and Taga clans, and the Yamauchi of Bingo Province.  Okihisa further requested support from the Ōuchi, while Tsunehisa made a corresponding request in writing.  Although without firm commitment to the cause, the Ōuchi decided to support Tsunehisa.  In a writing by Sue Okifusa, a senior retainer of the Ōuchi, he noted that Okihisa was in a direct confrontation with Tsunehisa, and that Okihisa had repelled repeated attacks by Tsunehisa.  He further confirmed that while the Ōuchi received requests from both of them, the Ōuchi ultimately decided to support Tsunehisa and reconciled with the Amago.

Tsunehisa prevailed in 1534, while Okihisa fled to Kōtachi Castle, held by the Yamauchi of Bingo Province.  He then incurred an attack by his nephew, Amago Akihisa, and killed himself.  His head was preserved in salt and sent to the Amago for inspection, while Tsunehisa’s second son, Amago Kunihisa, inherited Okihisa’s territory.  Meanwhile, Oki Tamekiyo, a kokujin from Oki Province, launched a rebellion that was quickly suppressed.  Akihisa invaded Mimasaka, bringing the province under the control of the Amago.  He then entered Bizen, gradually expanding his influence to the east.  Akihisa joined the Ōtomo in an encirclement campaign against the Ōuchi.

Succession as head of the clan

In 1537, Tsunehisa transferred control of the clan to Akihisa (later known as Haruhisa). Akihisa was Tsunehisa’s grandson (the second son of Amago Masahisa, Tsunehisa’s eldest son).  The following year, Akihisa attacked and captured the Iwami Ginzan silver mine from the Ōuchi.

Conflict between the Ōtomo and the Ōuchi continued during which the Amago maintained a tenuous peace with the Ōuchi.  Akihisa extended his influence to the east in an overwhelming victory against Akamatsu Masasuke, military governor of Harima Province, causing Masasuke to seek temporary refuge in Awaji Province.  In 1539, the Bessho clan in Miki Castle pledged support to the Amago, after which Masasuke fled to the metropolis of Sakai.  While Akihisa contemplated a march to Kyōto, the Ōtomo reconciled with the Ōuchi at the expense of the Amago, and seized the Iwami Ginzan silver mine. Furthermore, the Ōuchi captured Satō-Kanayama Castle, home base of the Takeda of Aki Province despite troops from the Amago sent to help the defenders.  Takeda Nobuzane escaped to Wakasa Province after which Akihisa withdrew to Izumo.

These events completely fractured relations with the Ōuchi.  In 1540, Akihisa mobilized forces based on desire for a final showdown with the Ōuchi and a request from Takeda Nobuzane to conquer the Mōri, kokujin from Aki allied with the Ōuchi.  The allegiance of surrounding forces favored the Amago, with over 30,000 mounted soldiers joining from neighboring provinces.  The large contingent laid siege to Yoshida-Kōriyama Castle, but despite preparing for the final showdown with the Ōuchi, lost the following year to an army comprised of 20,000 mounted soldiers under the command of Sue Takafusa. Takafusa led his army into battle after praying for victory at the Itsukushima Shrine. The Amago thereby lost control of Aki Province in the Battle of Yoshida-Kōriyama.

In 1541, Tsunehisa died in Gassantoda Castle at the age of 83.

Character

Tsunehisa, similar to Hōjō Sōun, typified the phenomenon of gekokujō, while, as a strategic genius, he was on a par with Mōri Motonari and Ukita Naoie.  He battled against Ōuchi Yoshioki and expanded the territory of the Amago clan.  For creating the foundation of the golden age of the clan (manifested in the era of his grandson, Amago Haruhisa), Tsunehisa was called the master of strategy.  Tsunehisa, Motonari, and Naoie are often referred to as the Three Strategists of Chūgoku.

Tsunehisa excelled in both the military and literary arts.  In his later years, he created a self-portrait.

Tsunehisa was known for being an extremely kind individual.  If retainers praised his possessions, he would delightfully give them away without regard to value.  As a result, the retainers were careful to observe but not comment upon his possessions.  On one occasion, when the retainers praised the branches on his pine tree, Tsunehisa attempted to dig-up the tree and give it to them, so those around him anxiously stopped him.  Even so, Tsunehisa did not give up, and instead he had the tree cut into firewood and presented to the retainers.  While others said it was unnecessary, he did not mind.  In another account, in the wintertime, he took off his kimono and gave it to retainers so was wearing only a thin silk short-sleeve shirt.  In one source, he is referred to as an innately selfless and upright individual.

Tsunehisa was known as being very thrifty.  He did not like when retainers cut melons in a manner that wasted any of the fruit so he delicately prepared them himself.