What happened
In 1221 the retired Emperor Go-Toba called warriors to arms against the regent Hojo Yoshitoki, aiming to overthrow the Hojo-led Kamakura shogunate. According to the Azuma Kagami, Hojo Masako’s rallying appeal to the vassals held the east together. Shogunate armies marched on Kyoto and won within about a month.
Background
After Yoritomo’s line died out, the court’s resentment of warrior rule had grown.
Consequences
Three retired emperors were exiled — Go-Toba to the Oki islands — and the shogunate installed the Rokuhara Tandai office in Kyoto to watch the court. Some 3,000 estates were confiscated from the losing side and redistributed to shogunate vassals. The war was the decisive reversal: from then on the warrior government stood clearly above the imperial court, a settlement that lasted until 1868.