A.  Turmoil in the Saitō Clan   

1. The Fall of Saitō Dōsan

Symbolized by the marriage of Sagiyama-dono to Nobunaga, the tenuous peace pact concluded between Dōsan and Nobuhide in 1548 had served the immediate needs of the warlords, but, after Dōsan’s fall from power, others in Mino who felt threatened by Nobunaga spurned the pact.  With respect to Mino, this undermined Nobunaga’s strategy to use political alliances as a means to further his campaign.

Dōsan had three sons, but he favored the younger two, Magoshiro and Kiheiji.  These sons demonstrated foresight and resourcefulness to a degree worthy of becoming his heir, but his eldest son, Yoshitatsu, caused concern.  Unlike the other two sons, Dōsan viewed Yoshitatsu as a stooge, cast by clan members as an outsider.  More importantly, rumors existed that Dōsan was not the natural father, and that Toki Yoriyoshi was the father of Yoshitatsu before Dōsan had accepted his wife, Miyoshino.  Yoshitatsu’s birth in 1527, just six months after their marriage, gave further support to the rumor.  Moreover, Yoshitatsu’s large build and bold features did not resemble those of his father or brothers. 

Confounded, Dōsan hoped to find a way that he could eliminate Yoshitatsu to allow one of his younger sons to become his successor.  A failure to do so would give the Toki clan an opportunity to regain control of the province by asserting that Yoshitatsu had a lineal connection to the Toki.  Dōsan reluctantly turned over control of Inabayama Castle to Yoshitatsu and withdrew to Sagiyama Castle in a form of temporary retirement.  He planned to wait for the right opportunity to banish Yoshitatsu in favor of one of his younger sons.

As for Yoshitatsu, he had little trouble anticipating a ploy by his estranged father to replace him with one of his brothers, and wasted no time in doing away with them in the same way that Nobunaga rid himself of his younger brother, Nobukatsu.  In 1555, Yoshitatsu colluded with Nagai Michitoshi, a younger brother of Dōsan, to carry out his plan.  Yoshitatsu feigned illness in order to lure both of them to Inabayama Castle, whereupon he had them ingloriously killed.  News of the incident infuriated Dōsan, making him even more eager to displace his renegade son.  By now, people regarded Yoshitatsu as the son of Yoriyoshi, so the patrons of the once-dominant Toki family rallied around him to restore the influence lost from Dōsan’s treachery.

Dōsan thought that once he rounded up local support, he would trounce the dull-witted Yoshitatsu, but, for the first time, Dōsan now found himself the odd man out, with few patrons.  More than a few adversaries aimed to settle scores with the aging and craggy man known as mamushi or the “pit viper.” Even though Dōsan put out the word for an attack on Yoshitatsu, he could only muster about two thousand men to his base at Sagiyama Castle.  Dōsan rose rapidly from humble origins without the benefit of a well-entrenched clan and loyal retainers.  Owing to his newly found support, Yoshitatsu succeeded in amassing an army of over twelve thousand men to oppose Dōsan.

In the ensuing battle in the fourth month of 1556, Yoshitatsu led his forces in a successful rout of the less numerous opponents, and Dōsan barely escaped.  After regrouping, Dōsan made a final pitch to overthrow Yoshitatsu in the Battle at Nagara River.  Once again, Yoshitatsu commanded his men to victory, demonstrating competence in positioning as well as the execution of his battle plans.  Nagai Chūzaemon chased him down on the run, and, in a pitiable finale, Komaki Genta knocked Dōsan down and took his head.  To the end, Dōsan had failed to see that Yoshitatsu could serve as a capable commander, and he paid with his life in a redemptive outcome for Yoshitatsu. 

Prior to his demise at the hands of Yoshitatsu, Dōsan had drafted a will to transfer control of Mino to Nobunaga.  After Yoshitatsu’s triumph, however, the will could not easily be enforced, and instead set the stage for an inevitable clash between Nobunaga and Yoshitatsu for control of the province.  This ended an eleven-year period of peace between the ruling clans in Mino and Owari provinces.

2.  Succession by Saitō Tatsuoki

After defeating Dōsan, Yoshitatsu benefited from the support of Oda Nobukiyo, Nobunaga’s uncle and lord of Inuyama Castle, located along the Kiso River in northern Owari.  Nobukiyo originally fought against the Saitō, but later betrayed the Oda.  With his support, the Saitō-controlled Ōgaki, Kitagata, Inabayama, Unuma, and Inuyama castles in a crest formation to apply pressure on Nobunaga’s base at Kiyosu.  Yoshitatsu, however, died unexpectedly at Inabayama Castle in 1561 after an illness at the age of thirty-five.  His wife and two children mysteriously died around the same time, leading some to believe that all of them perished as divine punishment for the killing of his younger brothers.  The death of Yoshitatsu soon after his defeat of Dōsan, as well as lingering ambiguity concerning Yoshitatsu’s origin as the son of Toki Yoriyoshi rather than Dōsan, further undermined the grip of the Saitō clan.

Amidst these circumstances, Yoshitatsu’s eldest son, Saitō Tatsuoki, became the new lord of Mino.  At fourteen years of age, Tatsuoki assumed his position at Inabayama Castle in the same year that he had his Coming-of-Age celebration, but Tatsuoki did not have long to savor the benefits of his new title.  Nobunaga had defeated the Imagawa, so he could turn his attention to Mino.  With Dōsan’s departure, Nobunaga no longer had any meaningful ties to the Saitō to inhibit him from testing the resistance of the youthful Tatsuoki, and saw this as an opportunity to exploit the vulnerability of the Saitō and to expand his influence in Mino.  He made plans to capture Tatsuoki’s headquarters at Inabayama, offering the benefit of a forward position from which to expand his territory.

In 1561, Nobunaga advanced into Mino along a front from Moribe to Karumi, setting up a camp in Sunomata.  Nobunaga entered Mino again the following month.  Despite the vulnerability of the clan owing to the succession, the Saitō relied upon powerful retainers known as the Mino Group of Three – Andō Morinari, Inaba Yoshimichi, and Ujiie Naomoto – to outflank the invading troops.  Tatsuoki suffered the bulk of over three hundred losses.

During this battle, Maeda Toshiie, an assistant of Nobunaga, killed Adachi Rokubei, a fierce warrior known as “Adachi the Slayer.”  Nobunaga proclaimed that Rokubei was so tough that killing him was equivalent to attacking and capturing a castle.  Nobunaga recognized this difficult accomplishment by forgiving Toshiie for his past transgressions.  This included the killing right in front of Nobunaga of a fellow retainer named Jūami, who had been skilled in the tea ceremony.  Shibata Katsuie and Mori Yoshinari successfully appealed to Nobunaga on behalf of Toshiie to spare him from severe consequences for the act, whereupon Nobunaga agreed simply to relieve him of his duties.  Toshiie spent the next two years as a wayfarer, seeking refuge from Tsubouchi Toshisada at Matsukura Castle located in the border area between Owari and Mino provinces.

Nobunaga admired Toshiie’s stage acting, an activity that allowed Toshiie to explore the more artistic and non-traditional side of his personality.  Toshiie had been on uncertain grounds even though he felled three of the Imagawa a year earlier at the battle of Okehazama.  His endurance and faithfulness epitomized the spirit of his fellow warriors.

The Battle of Moribe marked a resumption of the rivalry and border clashes that Nobuhide and Dōsan had subdued by the marriage pact.  Mino was an expansive province defended by over twenty thousand men.  At the time, Nobunaga controlled five thousand troops at most.  The end of the alliance between the Oda and the Saitō, in addition to the threat posed by the Imagawa to the east and continuing discord within Owari, marked a difficult period of struggle for Nobunaga.

B.  Advances by the Oda

1. Alliance with Tokugawa Ieyasu

Tokugawa Ieyasu, who had led the group of men to topple Marune fortress during Yoshimoto’s fateful excursion into Owari, along with the remainder of the Imagawa forces, fled to their respective home provinces.  Following the defeat at Okehazama, Ieyasu notified Imagawa Ujizane that he would remain allied to the Imagawa, but desired to return to his home province of Mikawa.  He acknowledged Nobunaga’s ascent to power in the region and opted for an alliance rather than risking loss through confrontation.  Ieyasu demonstrated patience, turning to the battlefield only when there were no alternatives to achieve his objectives.      

In 1561, Mizuno Nobumoto, Ieyasu’s uncle, delivered a message from Nobunaga to propose an alliance.  Ieyasu needed to decide whether to retain his ties with the Imagawa or enter into a new relationship with the Oda.  Some of his retainers urged him to remain loyal to the Imagawa, but, instead, Ieyasu paid a visit to Nobunaga at Kiyosu Castle the following year.  Having set his sights on Mino to the north, Nobunaga sought peace with his capable peer from Mikawa.  The Matsudaira illustrated the phenomenom of gekokjō by rising in stature from a kokujin status in the mountainous regions of Tōtōmi to become a powerful regional clan in Mikawa.  This made an alliance imperative to Nobunaga, enabling him to secure his eastern flank.  At the time of this initial meeting, Nobunaga was twenty-eight years old, eight years senior to Ieyasu.  Their alliance endured through untold turbulence over twenty-two years.

2.  Relocation to Komakiyama Castle

Mino Province served as a bridge between the eastern and western portions of Japan. The Tōzandō traversed the province, an offshoot of the Tōkaidō  known as the Mino road that ran south to Owari, and the Nagara and Kiso rivers.  In addition to transportation routes, Mino became an economic center owing to its strategic location and the fertile river valleys of the Nobi Plain.  During the Saitō era, systems of commerce and distribution blossomed.  Recognizing the importance of Mino to his bid for national conquest, Nobunaga made plans to move his headquarters from Kiyosu Castle to Komakiyama Castle in Mino.  Komakiyama stood only twenty kilometers from Inabayama Castle.  Securing that site would increase pressure on the Saitō, but many retainers originated from Kiyosu and had strong local roots, so he needed to cultivate their support. 

Prior to the announcement, he went on horseback with some of his retainers to the peak of Mount Ninomiya in northern Owari from which to peer at Inuyama Castle.  Mount Ninomiya rose in the midst of an undulating series of peaks and valleys, making it arduously difficult to ascend.  Noting that the Saitō-controlled castles of Inabayama, Sarubami, and Unuma were within hailing distance of this location, Nobunaga informed his retainers that, for strategic reasons, Mt. Ninomiya would be a desirable location for a new castle.  This news discouraged men accustomed to the conveniences of living in the environs of Kiyosu Castle.  None, however, raised their concerns to Nobunaga.  After a while, he called them together to announce his decision to move his headquarters the seventh month of 1563 to Komakiyama in Mino rather than Mount Ninomiya.  Located on the broad Nobi Plain near Kiyosu, Komakiyama offered a more habitable environment than Mount Ninomiya, the contingent enthusiastically supported the decision.  Nobunaga may have suggested the plan to move to Mount Ninomiya so that, upon the announcement of his true intentions, the men would embrace the decision rather than ponder the inevitable difficulties of the relocation. 

The next year, Nobunaga captured Inuyama Castle from Oda Nobukiyo, using it as a base to execute a military campaign in the eastern portion of Mino.  Niwa Nagahide then led a successful attack on Sarubami Castle.  Meanwhile, Hideyoshi negotiated with Ōsawa Masahide, lord of Unuma Castle, convincing him to turn over the castle without a fight. This achievement followed in the wake of Hideyoshi’s success at Sunomata.  When Masahide came to pledge allegiance to Nobunaga, Nobunaga understood his value, and pondered the consequences if Masahide later betrayed him and rejoined the Saitō.  In the end, Masahide remained under Hideyoshi’s command, earning control of a fiefdom yielding two thousand six hundred koku.

3. Rebellion by Takenaka Shigeharu

Saitō Tatsuoki surrounded himself only by those retainers whom he fancied, and treated others as outcasts.  One such individual was Takenaka Shigeharu, lord of Bodaiyama Castle and a small fief of ten thousand koku.  Tatsuoki did not favor Shigeharu. Meanwhile, Shigeharu doubted whether Tatsuoki and his close advisors could protect the clan in light of the growing threat from Nobunaga.  In 1562, Shigeharu met with his father-in-law, Andō Morinari, to discuss his opposition to Tatsuoki.  Morinari also looked upon Tatsuoki with disfavor, and lent a sympathetic ear to his younger counterpart.

In 1564, Shigeharu and a group of about fifteen men paid a visit to Inabayama Castle under the guise of meeting Shigeharu’s younger brother, who had taken ill.  Using weapons brought in disguised as gifts, they launched a covert rebellion and forced Tatsuoki to flee.  The plot enabled Shigeharu to capture Inabayama Castle without a perilous attack against the stronghold.    

Upon hearing the news of Shigeharu’s successful rebellion, Nobunaga immediately dispatched a messenger to carry the will given from Dōsan to Nobunaga showing Dōsan’s intention to grant Mino to Nobunaga.  It read that Nobunaga offered to give Shigeharu half of Mino in exchange for Inabayama Castle and control of the remainder of the province, but Shigeharu rejected the offer, and, after one year, sent his own messenger to Tatsuoki, requesting that he pay a visit to the castle.  In disbelief, Tatsuoki returned to the castle, delighted to find out that Shigeharu had decided to turn it back to him. Shigeharu hoped that by eliminating Tatsuoki’s close retainers, he could shake up the command and set it straight, but, to his disappointment, Tatsuoki resumed an unsettling course of leadership.

D.  The Rise of Toyotomi Hideyoshi

Toyotomi Hideyoshi began as a manservant for Matsushita Yukisuna, a retainer of Imagawa Yoshimoto.  Four years later, he advanced to the position of foot soldier.  The Imagawa had learned that the Oda soldiers wore light armor, and wanted to know if it was an improvement over the traditional attire.  The Imagawa gave Hideyoshi some money and ordered him to obtain a set of this armor.  He left on this mission, but decided to join sides with the Oda and never returned to Mikawa.  He began his service in the Oda army in 1554 at the age of eighteen, just three years junior to Nobunaga himself.  Hideyoshi’s passionate character and magnetic personality attracted the attention of Nobunaga while Hideyoshi served in the lowest ranks of his army. 

Demonstrating Nobunaga’s practice of valuing merit over pedigree as a standard for his men, in 1564, he provided Hideyoshi an opportunity to shine by ordering him to assist in pacifying the local samurai, known as jizamurai, in Mino.  The first round of clashes ended in a sorrowing defeat for Nobunaga.  Takenaka Shigeharu took the lead in setting up a strategic ambush that nearly decimated Nobunaga’s forces.  A small contingent of locals set out to stage a frontal maneuver, drawing them back into territory, while larger forces lying in wait attacked on both flanks.  Hideyoshi’s brilliance allowed the army to escape total defeat, and Shigeharu became known as a formidable opponent among Nobunaga’s men.

This early crushing defeat compelled Nobunaga to reconsider his strategy for Mino. Instead of trying to overwhelm the Saitō by force, he relied upon the talents of Hideyoshi to entice Shigeharu and the Mino Group of Three.  Nobunaga knew that by drawing these veterans to his side, he could undercut any resistance to his designs for Mino.  

The decision by all members of the Mino Group of Three to collude with Nobunaga reflected a common conviction that the young and dissolute Tatsuoki posed an unworthy successor to his father destined to bring about the collapse of the Saitō clan.  Further, Tatsuoki had a reputation for alienating retainers whom he disliked.  This made their betrayal a natural alternative for the members of the Mino Group of Three, none of whom felt any sense of kinship with the capricious young lord.  Ujiie Naomoto preceded his two partners by joining forces with Nobunaga in 1564, with the others following soon thereafter.

By 1564, Nobunaga had subjugated eastern Mino and controlled the territory around Inabayama Castle – an impregnable fortress and stronghold of the Saitō clan.  Situated on a highland, the Kiso, the Nagara, and the Ibi rivers protected the approach to the castle.  These flowed below the east and west sides of the castle, crisscrossed by an assortment of tributaries forming a large swampy area that served as a natural barrier to the movement of troops.  Sunomata lay five kilometers upstream in a delta region at the convergence of the Kiso and Nagara rivers – an ideal location to establish a beachhead from which to launch attacks against Inabayama Castle.  

Soon after the end of the rainy season, Nobunaga ordered Sakuma Nobumori to lead forces into Mino and secure the beachhead.  Nobumori entered the province with several thousand troops, porters, and workers to build the fort at Sunomata.  Scouts operated day and night to warn of an impending attack.  The Saitō nervously observed the activity without taking action.  A week passed, two weeks, then one month, and the scouts were more at ease.  Two months after commencing the work, the outside of the fort neared completion.  The Saitō chose this time to launch a pre-dawn attack that caught Nobumori and his forces off-guard.  Almost one thousand men died; the remainder fled to Kiyosu Castle.  The fort turned to ashes.

Despite the loss, Nobunaga remained committed to establishing a base in Sunomata.  For the second attempt, he ordered another bushō, Shibata Katsuie, to lead another force into Mino.  Katsuie arranged for a large contingent of workers to haul logs and stones to the site under the watchful eyes of the Saitō.  The rainy season began and the work bogged down.  Although an accomplished commander, Katsuie had little patience to supervise the hoards of laborers on the construction site.  The Saitō infiltrated the site with informants to provide timely details on the activities underway.  Before long, the Saitō launched a nighttime attack, and, although the Oda troops stood ready, they could not ward off the enemy.  Many of the men in the Oda contingent served as common laborers with no experience in battle.  When they panicked and fled the site, the remaining forces lost their will to fight and followed suit.  Once again, the Saitō destroyed the base. 

Sunomata pointed like a dagger at the throat of the enemy, so Nobunaga continued his efforts to gain a foothold.  He appointed Oda Nobukiyo to lead the contingent, but before Nobukiyo could undertake his assignment, he died in a nearby battle. 

Finding Hideyoshi to be a free thinker, Nobunaga solicited his opinion.  Hideyoshi discussed the reconstruction of a span of exterior wall that had once collapsed at Kiyosu castle.  Although twenty days had passed, the workers had repaired less than twenty percent of the wall.  Hideyoshi believed that, given the opportunity, he could have the project completed in a few days.  His proposal called for dividing the laborers into ten teams, each responsible for ten percent of the wall.  He would then have them compete for a monetary award.  This approach required higher outlays to the workers, but he felt confident the men would complete the work in short order.  Nobunaga agreed to the plan and placed Hideyoshi in charge of the laborers.  Hideyoshi impressed Nobunaga by completing the project as promised.   

Nobunaga believed that Hideyoshi may be able to devise a creative solution for the problems confronted in Mino, so, in 1566, he ordered Hideyoshi to build Sunomata castle.  This assignment gave Hideyoshi the opportunity to demonstrate his abilities as a strategist and leader.  In his earlier days as a wayfarer, Hideyoshi had traveled throughout Mino and Owari provinces, making a network of friends and acquaintances – an assorted mix of ruffians, thugs, and bandits who had no association with any regional warlord.  They were opportunistic, joining bands as seen fit, doing whatever they could to survive from one day to the next.  The worst of them engaged in acts of thievery and killing; others lived in villages or tended the fields in the countryside.         

Hideyoshi informed Nobunaga that if he offered adequate compensation, he could form a large band of these characters from the Kiso and Nagara river area to set up a camp and build a fortress in Sunomata.  The men would serve as defenders and laborers.  Nobunaga approved the final plan, and Hideyoshi zealously carried out his orders.  He amassed a contingent of upwards of five thousand men, including as many as one thousand two hundred warriors and eager subordinates such as Hachisuka Masakatsu and Maeno Nagayasu.  Hideyoshi delivered the building plans to Masakatsu, who, in turn, assigned work to the laborers in accordance with the plan.  The workers set about cutting trees upstream from the site, strapping the logs to rafts, and floating them down river.  They paid no heed to local people who attempted to interfere with their activities, threatening them with violence when necessary.  The men quickly gathered and delivered the logs and materials to Sunomata, where they worked feverishly to untie the logs, and cut them to size with saws and hatchets.  Other teams of men used these to build the main structure and its towers. 

Noticing the rapid pace of the construction, the Saitō made another mass assault, but could not breach the sturdy fences erected around the perimeter of the construction site.  Meanwhile, Hideyoshi’s men rained a barrage of gunfire on them and repelled them with spears.  The Saitō tried three times to attack, only to lose more of their men.  This success enabled the construction to continue.  In just ten days, the laborers built ten turrets, constructed two thousand kan of walls, and assembled fifty thousand logs.

Hideyoshi built the stronghold at Sunomata in such a short time that locals referred to it as the one-night castle.  Nobunaga capitalized on the strategic base to launch an attack and corner Tatsuoki at his headquarters in Inabayama castle.  Confident of his victory, Nobunaga commenced major construction work on the town below without waiting for the surrender.  Meanwhile, the Mino Group of Three captured hostages and partook in the siege of the castle.  Nobunaga inspired them by carrying out his plans with avid determination.

In 1567, Nobunaga directed his forces against Inabayama castle with as many as twelve thousand men.  Unable to withstand the assault without further support, Tatsuoki found an escape route to flee to Ise-Nagashima, and then to the northern province of Echizen, where the ruling Asakura clan offered refuge.  Soon thereafter, Nobunaga moved to Inabayama castle to take advantage of its location.  Nobunaga invited many former patrons of the Saitō to join his army, including senior commanders, such as Hineno Hironari, who had earlier opposed him on the battlefield.  Nobunaga knew that if he could secure the loyalty of capable men such as Hironari, they would strengthen his own position.  Nobunaga even assigned control of Kajita Castle and a fief to Tatsuoki’s younger brother, Toshiharu.  Takenaka Shigeharu remained a close ally of Hideyoshi, and the Mino Group of Three continued to serve as loyal retainers in Nobunaga’s army.   

After defeating Tatsuoki, Nobunaga remained in Mino, which was closer to Kyōtō, separated only by Ōmi Province.  He renamed Inabayama to Gifu Castle and pressed ahead with his campaign.  Nobunaga authorized free markets under a policy known as rakuichi-rakuza in the town below the castle.  This environment attracted merchants, stimulated commerce, and generated revenue to fund the further expansion of his campaign.

The subjugation of Mino served as a touchstone in his meteoric rise to power.  He now commanded over thirty thousand men in Owari and Mino, and had the support of another ten thousand men under alliance with Tokugawa Ieyasu of Mikawa and Azai Nagamasa of Echizen.  This rapidly growing army placed him in contention with other regional powers including the Mōri, the Takeda, and the Uesugi.  Henceforth, he used the seal enscribed “tenka fubu,” meaning to rule the empire by force. 

Recognizing the limits of his power at the time, Nobunaga reached out to form loose alliances with the Uesugi and the Takeda.  Their spheres of influence were sufficiently far away from the territory under Nobunaga’s control to avoid conflict, and the truce with Nobunaga proved mutually beneficial in light of the tension in the eastern provinces exisiting between the Hōjō, the Takeda, and the Uesugi.  Nobunaga acted with respectful deference toward these senior warlords to remain in their good graces.  In so doing, he demonstrated the foresight to neutralize potential threats to his growing influence, as well as those confronting him in his own region.