Battle of Hiratsukahara
Date: 10/20 of Genki 1 (1570)
Location: Hiratsukahara in the Niihari District of Hitachi Province
Synopsis: The Oda clan were a powerful daimyō family based in the south of Hitachi Province, but, under pressure from the Satake clan in the north of the province as well as Uesugi Kenshin of Echigo, the power of the Oda began to wane. Yūki Harutomo, a sengoku daimyō of neighboring Shimōsa Province, took the opportunity to invade the territory of the Oda. Following a violent field battle, and despite the superior numbers of the Yūki army, the Oda launched a nighttime attack that caught the Yūki off-guard and sent them fleeing in defeat.
The Battle of Hiratsukahara occurred on 10/20 of Genki 1 (1570) in Hiratsukahara in the Niihari District of Hitachi Province. The violent field battle was waged between Oda Ujiharu, a bushō and sengoku daimyō of Hitachi and Yūki Harutomo, a bushō and sengoku daimyō of Shimōsa Province.
The Oda clan of Hitachi and Yūki clan of Shimōsa were powerful daimyō families counted among the Kantō-hachiyakata, or Eight Noble Families of the Kantō. Their territories were separated by the Kinu River and, after repeated battles, the clans became archenemies. At the end of the Sengoku period, during the era of Oda Ujiharu and Yūki Harutomo, the conflict between the clans persisted, marked by the Battle of Ebigashima in 1556 and the Siege of Yūki Castle in 1561.
In Hitachi, another rivalry existed between the Oda (based in the south) and the Satake clan (based in the north). In the era of Satake Yoshiaki, the Satake expanded their authority, causing the submission of the Edo clan of northern Hitachi and the Daijō clan of the central portion. His heir, Satake Yoshishige, sought to unify the entire province, gradually encroaching on the territory of the Oda in the south. Meanwhile, in the era of Oda Ujiharu, the Oda clan was caught in-between the Satake clan and the Uesugi clan of Echigo Province, resulting in a decline of their influence. Yūki Harutomo of Shimōsa viewed this as a favorable opportunity to invade the territory of the Oda.
Course of Events
On 8/13 of Genki 1 (1570), Yūki Harutomo departed Yūki Castle and traversed the Funadama crossing on the Kinu River and, with Tagaya Masatsune, the lord of Shimotsuma Castle, leading the vanguard, invaded the territory of the Oda clan. One party headed to pin-down Ishige and Toyota castles while the main division proceeded from Yagihara, passing-through Mizumori on the approach to Ōzone. In Ōzone, Asano Gorōzaemon and Asano Tōemon, allies of the Oda, defended a fortress, but the invading forces chased them away. Next, the invaders ousted Satō Yazaemon of Wakashiba and Satō Kanbei and Satō Jinshichirō of Tamatori, decimated the head of the Hasunuma manor, and, at night, killed Mimura Saburō Daibu of Kuchinohori. The army then went from Sakkabe to Hiratsukahara while another group established the main base for the Yūki at the Anraku Temple in Sakao.
In response to the invasion by the Yūki army, the main division of the Oda army under Oda Ujiharu went to Hiratsukahara to set-up an opposing position. Others deploying to Hiratsukahara included troops led by Nonaka Sezaemon Nyūdō Donsai (the lord of Karima Castle), Yoshihara Echizen (the lord of Uenomuro Castle), and Ōtsu Nagato (the lord of Hanamuro Castle). Hiratsukahara, an approximately 2.5 mile square field, served as the scene for a chaotic battle between the opposing armies. After a day of battle, neither the Oda nor Yūki emerged as a victor between the evenly-matched forces and both sides pulled back. The Yūki established a position at Takatadai while the Oda forces retreated to Ōhashi in Karima and made a base on Mount Myōjin.
Sugenoya Masasada of Fujisawa Castle headed-out in support of the Oda, traversing the Sakura River and arriving at Kurihara to observe the status of the enemy forces. The vanguard forces of the Yūki were at Takatadai while the main base of Yūki Harutomo was at Sakao, but the day came to an end so the battle was deferred to the next day. The Yūki forces, however, had a superior number of forces so the Oda forces attempted to launch a nighttime attack against the main base of Harutomo. At that moment, under cover of darkness and without making a sound, at Ichinoyahara, the troops split into three groups. A group comprised of members of the Ishidō and Hyōdō went around from Sakkabe to the eastern entrance to Sakao, the Numajiri forces set ambushes in western Sakao, and the troops led by Sugenoya Masasada headed from Nakane to Kuchibori. While the Yūki forces were caught off-guard, the Oda forces took the opportunity to launch a surprise attack and set fire to their main base. In the course of a major defeat, the Yūki forces fled to Yoshinuma. Meanwhile, after observing from afar the fire at the main base, the division led by Tagaya Masatsune positioned at Takata rushed to the scene, but was then decimated after running into the ambush set by Numajiri Matagorō, with surviving forces heading via Tegomaru to Yoshinuma.
This battle reaffirmed to other daimyō in the Kantō the power of Oda Ujiharu. In the latter part of the Eiroku era (1564 to 1570), Ujiharu was forced into bitter battles against Uesugi Kenshin of Echigo and Satake Yoshishige of Hitachi. Nevertheless, his defeat of the numerically superior forces of Yūki Harutomo in this battle had reverberations for Ujiharu’s resistance toward Yoshishige for the following two decades.