Second Battle of Kōnodai
Date: Eiroku 6 and 7 (1563 to 1564)
Location: Sagamidai in the environs of Kōnodai Castle in Shimōsa Province
Synopsis: Ōta Yasusuke, a retainer of the Hōjō, defected from the clan. To protect him, Uesugi Kenshin requested Satomi Yoshihiro to deploy with his forces and he was soon confronted by a larger Hōjō army deployed from Edo Castle. After prevailing in the first stage of the battle, the Satomi enjoyed a banquet with saké, after which they incurred an unexpected nighttime attack by the Hōjō that left them fleeing in disarray.
The Second Battle of Kōnodai occurred in Eiroku 6 and 7 (1563 to 1564) in Sagamidai in the environs of Kōnodai Castle in Shimōsa Province. The conflict was waged between the Satomi army under Satomi Yoshitaka and the Hōjō army under Hōjō Ujiyasu.
After the First Battle of Kōnodai, the area of Kōnodai was occupied by Takagi Taneyoshi, a retainer of the Chiba clan and the lord of Kogane Castle. When the Chiba clan came under the command of the Hōjō, the area by default became the territory of the Hōjō.
In 1563, after Hōjō Ujiyasu and Takeda Shingen combined to attack Matsuyama Castle (aligned with the Uesugi clan) in Musashi Province, Satomi Yoshitaka, upon the demand of Uesugi Kenshin, dispatched his lineal heir, Satomi Yoshihiro to support the defenders. These reinforcements clashed with the Hōjō army at Kōnodai in a bid by the Hōjō to stop them. At this time, the Satomi army, with the support of Ōta Sukemasa (aligned with the Uesugi), entered Musashi but Matsuyama Castle fell to the attackers so both armies withdrew.
Course of events
Toward the end of 1563, Ōta Yasusuke, the commander in charge of defending Edo Castle who was under the command of Hōjō Ujiyasu, despised Ujiyasu so, via Ōta Sukemasa, he attempted to abandon his lord in favor of Uesugi Kenshin. This plan failed and he fled for the protection of Sukemasa. Upon request of Kenshin, Satomi Yoshihiro deployed early the next year to rescue Sukemasa and Yasusuke, leading a large army from Bōsō (meaning Awa, Kazusa, and Shimōsa provinces). On 1/4, this army totaling 12,000 soldiers arrived at Kōnodai Castle. Determining that it would be futile to attempt to intercept the opposing forces on their own, the Chiba clan requested reinforcements from Ujiyasu. In response, a Hōjō army totaling 20,000 soldiers immediately deployed.
On 1/7, the Hōjō army departed Edo Castle and attacked the Satomi army. Tōyama Tsunakage and Tominaga Naokatsu, commanders in charge of defending Edo Castle, served with the vanguard forces. Bearing responsibility for failing to detect Yasusuke’s defection, they charged ahead of the main division under Hōjō Tsunashige. After passing near the environs of the present-day Yakiri Crossing, they traversed the Edo River and attacked at Kōnodai and Mama. While climbing a steep hill on a plateau, they encountered an ambush by soldiers from the Satomi army. The men attempted to withdraw toward a bridge to Mama but were killed in action and Tsunakage’s son-in-law, Toneri Gentazaemon Tsunetada, the lord of Toneri Castle, also died. Yasusuke and Takagi Tanetoki (Taneyoshi’s son) were also relatives of the Tōyama clan through a daughter and sister of Tsunakage.
A daughter of the Tōyama married to Toneri Tsunetada bore a son named Yūmaru and after the death of Tsunetada remarried with Daidōji Masashige. Yūmaru was adopted by Masashige and later adopted the name of Daidōji Hayato (Daidōji Naohide).
The defeat in this battle completely upset the plans for a joint operation between the Chiba army (including Takagi Tanetoki) and the Hōjō army to launch a pincer attack against the Satomi army.
Pleased with the victory and considering that the deployment occurred early in the new year, Satomi Yoshihiro treated the soldiers to saké. Given that the Tōyama and Tominaga scattered early, the Hōjō were able to preserve their main division and pretended to withdraw. Then, at dawn on the eighth, they crossed the Edo River again and launched a nighttime attack against the Satomi army. Their approach was via a detour in the southern portion of Shimōsa (in the direction of Suwada) which was a plateau of relatively gentle terrain. Finding themselves under attack after the festivities, the Satomi army fell into disarray. Moreover, through the devices of the Hōjō, Toki Tameyori, a mainstay of the Satomi army, betrayed Yoshihiro and left the battlefield. Masaki Nobushige, the head of the senior retainers, was killed in action. Likewise, a senior retainer named Anzai Sanemoto served as a substitute for Yoshihiro and just before the battle, he was rescued by Sakai Taneharu, the lord of Toke Castle in Kazusa, who was late to arrive after defecting to the Satomi clan so Yoshihiro just managed to flee the battlefield in time.
In any event, after the battle in 1564, the Hōjō army advanced at once into Kazusa Province, subduing Toki Tameyori followed by Masaki Tokitada (the younger brother of Masaki Tokishige). Although in a difficult situation, the Satomi army engaged in active operations to contain the Hōjō army. According to one theory, the Satomi recaptured Sanuki Castle (the base of Yoshihiro that have been occupied for a long time by the Hōjō army) after this Second Battle of Kōnodai. After a victory at the Battle of Mifuneyama in 1567, the Satomi undermined the conquest of Awa Province by the Hōjō and the status between the two armies reverted to a stalemate.
Reassessment of the dates
Based on recent research, the prevailing view is that the course of events describing this battle mix-up details from a battle in the first month of Eiroku 6 (1563) and the first month of Eiroku 7 (1564). The occurrence of a genuine battle in 1563 is substantiated from sources. Meanwhile, records which previously were deemed to apply to events in 1564 cannot simply be deemed to be erroneous. There is a record of a surprise attack at dawn on 1/8 of Eiroku 6 (1563), and there is a document issued by the Hōjō clan dated 2/18 of Eiroku 7 (1564) regarding the scattering of the Satomi army.
In Sawada Park in the city of Ichikawa in Chiba Prefecture, there was a small hill called Taikozuka. There is a legend that the Satomi army pounded on a taiko drum to sound the alarm that the Hōjō army had launched a surprise attack on their main base.
The ruins of Kōnodai Castle were redeveloped as Satomi Park. At the site of these ruins stands a memorial tower to the members of the Satomi army built in the eleventh month of 1829 during the latter part of the Edo period.