After Yoshimoto's death and his legitimate son Ujizane IMAGAWA succeeded the family reign, Motoyasu MATSUDAIRA (later Ieyasu TOKUGAWA) declared independence in Nishimikawa (western part of Mikawa Province), taking advantage of the unguarded moment.
義元の戦死により家督は嫡男の今川氏真が継いだが、この隙に乗じた松平元康（後の徳川家康）が西三河で自立。