Battle of Kitsunebashi
Date: 8/16 of Tenbun 14 (1545)
Location: Kitsunebashi in Imai in Suruga Province
Synopsis: In 1537, the Imagawa clan of Suruga forged an alliance with the Takeda clan of Kai. This marked the end of previously friendly relations between the Imagawa and the Gohōjō of Sagami, giving rise to a conflict over control of the Katō area in the eastern portion of Suruga. After numerous failed attempts, Imagawa Yoshimoto finally defeated the Gohōjō at Kitsunebashi and, as a condition of settlement, reclaimed the Katō area.
The Battle of Kitsunebashi occurred on 8/16 of Tenbun 14 (1545) as the first battle in the Second Katō War. In this conflict, the army of Imagawa Yoshimoto (a sengoku daimyō and the eleventh head of the Imagawa clan of Suruga Province) defeated the army of Hōjō Ujiyasu (a sengoku daimyō and the third head of the Gohōjō clan of Sagami Province) at Kitsunebashi in Suruga Province. Riding the momentum of this victory, Yoshimoto then captured Nagakubo Castle from the Gohōjō. Thru mediation by Takeda Shingen, Yoshimoto reclaimed the Katō area (the Suntō and Fuji districts of Suruga) from the Hōjō.
The Katō area was comprised of the territory to the east of Mount Fuji in the eastern portion of Suruga Province. Originally, the Imagawa clan of Suruga and the Gohōjō of Sagami maintained friendly relations. In 1537, however, after the Imagawa and Takeda forged an alliance through the marriage of the daughter of Takeda Nobutora (Jōkeiin) to Yoshimoto, relations were severed with the Gohōjō. Thereafter, the Katō area was disputed between the Imagawa and the Gohōjō clans. On 2/26 of Tenbun 5 (1536), Hōjō Ujitsuna (the father of Ujiyasu) forcibly took possession of the territory from Yoshimoto (who had recently become the head of the Imagawa clan) by launching a pincer attack with the Horigoe and Ii clans of Tōtōmi Province. This is known as the First Katō War. Thereafter, Yoshimoto attempted on several occasions to reclaim the lost territory by force. Finally, after Ujitsuna died and was succeeded by Ujiyasu, Yoshimoto joined forces with Yamanouchi-Uesugi Norimasa, the deputy shōgun of the Kantō from Kōzuke Province. Yoshimoto then planned a pincer attack against Ujiyasu. With additional support from the allied Takeda Shingen, Yoshimoto could pressure the Gohōjō clan.
On 7/24, Yoshimoto traversed the Fuji River and set-up an encampment at the Zentoku Temple. On 8/15, the Takeda army arrived at the Taiseki Temple but this was in anticipation of a settlement so were not prepared for battle. On 8/22, the Imagawa army led by Yoshimoto defeated the Hōjō army led by Ujiyasu at Kitsunebashi. Riding the momentum, in the ninth month, Yoshimoto toppled Yoshiharu Castle, followed by Nagakubo Castle. Around this same time, the Hōjō were surrounded at Kawagoe Castle by the allied forces of the Yamanouchi-Uesugi and Ōgigayatsu-Uesugi forces. This is known as the Siege of Kawagoe Castle. The Hōjō were abandoned even by Ashikaga Haruuji, the Koga kubō, who they had supported. Confronted with a precarious situation, Ujiyasu entered into negotiations with Yoshimoto mediated by Shingen. At the end of the tenth month, a settlement was reached on the condition that the Katō area be transferred to the Imagawa clan.