However, under the circumstances that a local lord, who was a former vassal of the Satomi clan, let out the information of the Hojo clan to the invading army, and the invasion by Misaki Navy was delayed for some reasons, the Mifune-yama fort fell to Yoshitaka and Ujimasa lost the control over Kazusa Province (Battle of Mifune-yama).
しかし、旧里見配下の国人が侵攻軍に内通し、三崎水軍の侵攻も遅滞した状況で、三舟山砦は義堯に大敗して上総の支配権を失った（三船山の戦い）。