Under circumstances where a confrontation between MINAMOTO no Yoritomo and his younger brother, MINAMOTO no Yoshitsune, got more serious after the fall of the TAIRA clan, Yoritomo held a memorial service for his father, MINAMOTO no Yoshitomo, on October 24, 1185, and Moritsuna also attended it.
平家滅亡後、源頼朝と弟の源義経との間で対立が深まっており、そうした中の文治元年（1185年）10月24日、頼朝は父である源義朝の供養を行い、盛綱もそれに列している。