The Miura clan, enjoying its political dominance by taking advantage of being the maternal relatives of the Hojo clan (warrior family of the Kamakura period, hereditary regents of the Kamakura bakufu (Japanese feudal government headed by a shogun), came into severe conflict with the Adachi clan, which also became the new maternal relatives of the Hojo family.
三浦氏は北条氏の外戚として勢威を振るっていたが、新たな北条家外戚となった安達氏との対立が激化する。