Battle of Unnotaira
Date: Fifth month of Tenbun 10 (1541)
Location: The Saku and Chiisagata districts of Shinano Province
Synopsis: Takeda Nobutora, the sengoku daimyō of Kai Province, joined forces with the Suwa and Murakami clans of Shinano in a bid to take control of the Saku and Chiisagata districts to divide among themselves. Soon after the withdrawal of Takeda forces, the Yamauchi-Uesugi entered to take back portions of the territory, while Nobutora was banished from Kai in a coup d’état orchestrated by his eldest son, Takeda Harunobu (Shingen).
The Battle of Unnotaira occurred in the fifth month of Tenbun 10 (1541) in the Chiisagata District of Shinano Province. The conflict was waged between an allied army comprised of Takeda Nobutora (a sengoku daimyō and the eighteenth head of the Kai-Takeda clan) and sengoku daimyō from Shinano including Murakami Yoshikiyo and Suwa Yorishige against an alliance of kokujin, or provincial landowners, in Chiisagata comprised of the Three Families of the Shigeno (the Unno, the Nezu, and the Mochizuki) led by Unno Munetsuna and Nezu Motonao with support from the Sanada clan (Munetsuna’s daughter was the mother of Sanada Yukutsuna).
Since the Muromachi period, the Ogasawara clan serving as the military governors of Shinano were unable to gain control of the province and, in the Sengoku period, the governing authority of the clan was limited. Provincial landowners competed among one another for influence on a local basis. In the eastern portion of the province, the Shinano-Murakami clan and the Shigeno clan (kunishū in the Chiisagata District) disputed over control of the area which, in 1468, led to the Great Battle of Unno.
The Murakami clan gradually pressured the Shigeno clan while commencing an invasion of the Saku District. In 1484, Ōi Masanori of the Ōi clan (kokujin in the Saku District) surrendered and the Murakami gained control of all of the district.
Meanwhile, in Kai Province which bordered the Saku and Chiisagata districts, the downfall of Takeda Nobumitsu, the military governor, in 1416, weakened the authority of this position and led to conflicts between influential kokujin. This event is known as the Revolt of Uesugi Zenshū, a battle in the Kantō between Uesugi Norimasa (Zenshū) who was the prior deputy shōgun of the Kantō, and Ashikaga Shigeuji who was the Kamakura kubō. In 1507, Takeda Nobutora inherited the headship of the Kai-Takeda clan. After he unified the province, Suwa Yorishige of the Suwa District in Shinano joined with kokujin in Kai to oppose Nobutora. In 1519, when Nobutora attacked Hiraga Castle in the Saku District, the Murakami clan deployed as reinforcements to the defenders whereupon Nobutora retreated after setting fires in the environs of Hiraga. This marked the first experience in battle for Murakami Yoshikiyo. In 1522, Nobutora attacked Ōi Castle, but was defeated by reinforcements from the Murakami.
In the ninth month of 1535, Nobutora reconciled with Suwa Yorishige and formed an alliance. Nobutora further established alliances with the Imagawa of Suruga Province as well as the Ōgigayatsu-Uesugi and the Yamauchi-Uesugi clans in the Kantō. In the eleventh month, the Takeda clan captured Unnokuchi Castle in the Saku District at the Battle of Unnokuchi. In 1539, a retainer of the Takeda named Obu Toramasa invaded Saku and fought against Murakami Yoshikiyo.
Violent clashes between the Murakami and Takeda armies escalated. In the second month of 1540, the Murakami army invaded Kai, and, in the fourth month, Itagaki Nobukata, a retainer of the Takeda, responded by invading Saku. As an outcome of these battles, the Murakami capitulated and the Takeda asserted control in the Saku District.
Course of events
While the Murakami and Takeda battled over control of the Saku District, the Shigeno family led by the Three Families of the Shigeno in the Chiisagata and Saku districts maintained their power as a rear guard for the Yamauchi-Uesugi clan who served as the deputy shōgun for Kantō of Kōzuke Province. In the fifth month of 1541, Takeda Nobutora of Kai formed an alliance with Suwa Yorishige and Murakami Yoshikiyo with the aim of invading the Saku and Chiisagata districts. The Takeda forces invaded the Saku District while the Suwa and Murakami forces invaded the Chiisagata District. Members of the Shigeno family led by Unno Munetsuna resisted, but Onoyama Castle (Ueda Castle) was toppled while, in Unnotaira and Yazawa, the defenders retreated in defeat from the allied army. Munetsuna’s eldest son, Unno Yukiyoshi, was killed in action during an advance by Murakami forces in Katsuo from 5/13 to 5/14 of Tenbun 10 (1541).
After the Shigeno families collapsed on 5/25, Unno Munetsuna, Sanada Yukitsuna, and Nezu Masanao relied upon assistance from Uesugi Norimasa, the deputy shōgun of the Kantō, to go into exile in Kōzuke Province. Thereafter, the movements of Munetsuna are uncertain and he is surmised to have died in Kōzuke.
After the battle, the Takeda, the Suwa, and the Murakami clans divided among themselves the territory of the Shigeno families. Among those who surrendered during the battle, there is reference to an individual named Yazawa-dono, which is interpreted as meaning Yazawa Yoritsuna, the younger brother of Sanada Yukitsuna. Yoritsuna then served on behalf of the Takeda, the Suwa, and the Murakami before returning to his home territory. Yoritsuna served Murakami Yoshikiyo when Yoshikiyo came into conflict with the Takeda, but, after Yukitsuna affiliated with the Takeda, Yoritsuna abandoned the Murakami. Nezu Motonao, a member of a band of bushi known as the Suwa shintō, was an adoptee of the Suwa clan and the rights to his territory were recognized. Meanwhile, Nobutora had an alliance with the Yamauchi-Uesugi clan so, on 6/4, Nobutora and his son, Harunobu, withdrew from Shinano.
On 6/14, after returning to Kai, Nobutora departed on a visit to Imagawa Yoshimoto, the sengoku daimyō of Suruga Province. During this visit, however, Nobutora was banished from Kai in a coup d’état by his eldest son, Harunobu. In the seventh month, upon request of Unno Munetsuna, Uesugi Norimasa had troops deploy to the Saku District under the command of Nagano Narimasa, the lord of Minowa Castle. Numerous families located in the district, including the Ōi, the Hiraga, the Uchiyama, and the Shiga surrendered without resistance. It is surmised that Unno Munetsuna and Sanada Yukitsuna participated in this Uesugi army but, after Nagano Narimasa settled with Suwa Yorishige, the army retreated without entering the former territory of the Unno clan in the Chiisagata District. This is regarded as a factor in the decision by Sanada Yukitsuna to leave the Uesugi in favor of serving the Takeda.
The Takeda clan witnessed a significant loss of authority with the Yamauchi-Uesugi in control of the Saku District and Murakami Yoshikiyo in control of the Chiisagata District. Suwa Yorishige settled on his own with the Yamauchi-Uesugi and territories were transferred. After inheriting the headship of the clan in the sixth month of 1541, one year later, in the sixth month of 1542, Harunobu disbanded the alliance with the Suwa clan, invaded the Suwa District, and destroyed the Suwa. It is surmised that Harunobu viewed the settlement and allocation of territory implemented by Suwa Yorishige on his own accord with the Yamauchi-Uesugi breached the alliance with the Takeda. Harunobu continued the invasion of Shinano and recovered the Saku District. In 1548, he invaded the Chiisagata District, engaging in direct conflict against the Murakami clan at the Battle of Uedahara and the Collapse at Toishi. Harunobu also made enemies with the Yamauchi-Uesugi clan.
Among the members of the Shigeno family who fled to Kōzuke, the whereabouts of Unno Munetsuna thereafter are unknown, marking the end of the Unno clan which was one of the well-known Three Families of the Shigeno dating from the Heian Period.
After the ouster of Nobutora, Sanada Yukitsuna, via an introduction from the Nezu clan, entered into service as a retainer of Takeda Harunobu. Yukitsuna was active in battles against the Murakami and Yamauchi-Uesugi clans. He succeeded in efforts to recover the Sanada township located in territory governed by the Murakami (although there are other theories in this regard).