In the Oei War in December 1399 he participated as a member of the army of bakufu with his eldest son Mitsuyasu KITABATAKE and had military exploits, but Mitsuyasu died in the battle.
そして応永6年（1399年）12月の応永の乱では、長男の北畠満泰と共に幕府軍の一員として参加し武功を挙げたが、満泰が戦死する。