Stories of the Japanese 00468 [Late Heian Period] The Battle of Kanasa Castle

November 1180. Koremori, having been defeated at the Battle of Fujigawa, returned to Fukuhara. Kiyomori was furious and ordered,
“Exile Koremori to Kikai-ga-shima,”
but he was stopped by those around him, and it was never carried out.
Meanwhile, Yoritomo's army was buzzing with their great victory. While they would have liked to advance their troops to Fukuhara as they were, that was not possible. This was because there were still many in the Kanto region who had not yet submitted to Yoritomo, such as:
・Ashikaga Toshitsuna (?:–1180?)
・Nitta Yoshishige (1114–1202)
・Shida Yoshihiro (?:–1184)
Because there were many such individuals, if Yoritomo were to leave Kamakura undefended to go and overthrow the Taira clan, there would be a risk of being caught in a pincer attack.
Since the Nitta and Ashikaga clans have appeared here, let us briefly introduce both. Going back in time to 1150, an incident occurred where Minamoto no Yoshikuni (1091–1155) was dragged off his horse by the retainers of Tokudaiji Saneyoshi (1096–1157) for allegedly being rude to Saneyoshi while visiting the Imperial Palace. Yoshikuni's angry retainers set fire to Saneyoshi's residence, and to avoid arrest, Yoshikuni retreated to his territory, the Ashikaga Manor in Shimotsuke Province (Ashikaga City, Tochigi Prefecture).
Two sons were born to that Yoshikuni. The eldest son, Yoshishige, settled in the Nitta Manor (Ota City, Gunma Prefecture) and began calling himself Nitta Yoshishige. The seventh-generation descendant of this Nitta Yoshishige is the famous Nitta Yoshisada.
Meanwhile, the second son, Yoshiyasu, settled in the Ashikaga Manor and began calling himself Ashikaga Yoshiyasu (1127–1157). The seventh-generation descendant of this Ashikaga Yoshiyasu is the famous Ashikaga Takauji.
Now, as for who the aforementioned Ashikaga Toshitsuna was, this is complicated, but he was a local warlord who had settled in the Ashikaga Manor, completely separate from the Ashikaga clan that began with Ashikaga Yoshiyasu. It is believed that there was likely no blood relation. It seems he was destroyed by Yoritomo at some point, but the details are unknown.
Regardless, because there were many warlords in the Kanto region who had not yet submitted to Yoritomo, Yoritomo could not head for Fukuhara-kyo. Therefore, it was decided to first subjugate the Satake clan of Hitachi (Ibaraki Prefecture). On October 27, Yoritomo and his men departed Kamakura to pursue and destroy Satake Hideyoshi (1151–1226).
On November 5, the battle began at Kanasa Castle (Hitachiota City, Ibaraki Prefecture), the residence of the Satake. Yoritomo's army induced Satake Hideyoshi's uncle, Yoshisue, to defect, and when Yoshisue shouted loudly into the castle from the rear, the inside of the castle fell into great confusion, and Satake Hideyoshi fled for his life. The battle ended in a great victory for Yoritomo.
On December 22, Nitta Yoshishige decided to submit to Yoritomo, and on January 11 of the following year, 1181, Kajiwara Kagetoki also decided to submit. Yoritomo was steadily increasing his allies.