After the second shogun, MINAMOTO no Yoriie, was expelled from the bakufu following the Conspiracy of Yoshikazu HIKI in October 1203, MINAMOTO no Sanetomo, who was 12 years old then, was backed up to become the third shogun and Tokimasa HOJO took the helm of the bakufu.
建仁3年（1203年）9月の比企能員の変・2代将軍源頼家の追放によって12歳の3代将軍源実朝が擁立され、北条時政が実権を握った。