In June 1180, Tadatsuna killed MINAMOTO no Kanetsuna and others during the hunt for Prince Mochihito and MINAMOTO no Yorimasa, who were raising an army to defeat the Taira clan (the Rising of Prince Mochihito).
翌年5月、平氏追討の兵を挙げた以仁王・源頼政の追討（以仁王の挙兵）にあたって源兼綱らを斬った。