Battle of Kanasa Castle

The Battle of Kanasa Castle (金砂城の戦い, Kanasajō no Tatakai) began on the night of 4 November 1180 (Jishō Calendar) or 22 November 1180 (Gregorian calendar), and ended on the 5th at Kanasa Castle in Hitachi Province (near present-day Hitachi-Ōta City, Ibaraki Prefecture) between the Minamoto clan led by Minamoto no Yoritomo and the Satake clan led by Satake Hideyoshi. It ended with a Minamoto victory.

The Satake clan held ties with the Taira clan, causing them to adopt an anti-Minamoto stance. After Yoritomo's victory at the Battle of Fujigawa, it was decided that rather than chase the pursuing Taira clan, the Satake should be subdued first, leading Minamoto forces to set out on 27 October and arrive at Hitachi Kokufu on 4 November.

Here, Hirotsune convinced Satake Yoshimasa to come alone to the center of Ōyabashi Bridge, where he was executed. This led to some of Yoshimasa's followers bowing and surrendering or fleeing. This was quickly followed by Hideyoshi further fortifying Kanasa, which was followed by a Minamoto full-scale assault on it. After hours of fighting, retainers delivered a message to Yoritomo at 4am the next day, notifying him that the castle "cannot be taken by human force".

This led to a meeting with Hideyoshi's uncle, Satake Masanari, where he was successfully convinced to defect in return for land gained through killing Hideyoshi. After the arrival of Masanari, defending forces fell into disarray at the unexpected defection, leading Hirotsune to push the offensive further and Hideyoshi to disappear without a trace.

At around 2am the following morning, the castle had its walls burned down and troops were sent to look for Hideyoshi. Despite a rumor about his whereabouts being near the Satake-controlled Hanazono Castle, Yoritomo didn't pursue Hideyoshi to it due to possible threats from the nearby Fujiwara clan. As a result of the victory, Hideyoshi's holdings were confiscated and redistributed as rewards for the warriors.