In the Battle of Sunomatagawa in 1181, he with his family took sides with the army of MINAMOTO no Yukiie, but was defeated, and Shigemitsu was killed by TAIRA no Morihisa, younger brother of TAIRA no Moritsuna (Takahashi saemon no jo) (May 2, 1181 Section of "Azuma Kagami" (The Mirror of the East)).
治承5年（1181年）の墨俣川の戦いで一族と共に源行家の軍勢に加勢し敗北、重満は平盛綱(高橋左衛門尉)の弟・平盛久に討ち取られた（『吾妻鏡』同年3月10日条）。