Adachi Yasumori

Adachi Yasumori (1231–1285) was a senior warrior official whose family was closely connected by marriage to the Hōjō regents. A son of Yoshikage, he became head of the Adachi household in 1253 and served on judicial panels and the governing council. These duties placed him where land disputes, service and access to office were decided. His position depended on administrative work and family connections as well as armed followers. [S01]

During the Mongol attacks, Yasumori supported Hōjō Tokimune’s government, helped organize defenses as military governor of Higo, and handled rewards for service. After Tokimune died in 1284, he assisted the young regent Sadatoki and backed measures protecting the rights of the shogunate’s warrior retainers. He competed with Taira no Yoritsuna, a powerful servant of the Hōjō ruling household. Both men worked within Sadatoki’s government, but drew strength from different networks around it. [S01, S02]

The conflict ended in the destruction of Yasumori and many relatives and supporters in 1285, in the event known as the Shimotsuki Incident. The Hōryakukanki, a later chronicle, explains the purge through Yoritsuna’s claim that Yasumori’s son sought the shogunate by asserting Minamoto descent. That account preserves an accusation, without proving the plan. The purge strengthened Yoritsuna’s position. It also ended Yasumori’s effort to keep influential warrior households involved in government alongside the Hōjō’s own servants. [S01, S02, S03]