姊川之戰
Masakatsu served Oda Nobunaga, under command of Toyotomi Hideyoshi, and may have participated in the building of Sunomata Castle (1567) and fought at the Siege of Inabayama (1568), also fought at the Battle of Anegawa (1570) against Azai and Asakura forces, as well as the campaigns against the Mōri. In 1585, Hideyoshi awarded him Awa Province as a fief, but he declined in favor of his son, Iemasa, serving instead as a close adviser of Hideyoshi.