Battle of Okehazama
By 1559 the leadership of the Oda clan had passed to Oda Nobunaga. In 1560, Imagawa Yoshimoto leading a large army of 25,000 men, invaded Oda clan territory. Motoyasu was assigned a separate mission to capture the stronghold of Marune. As a result, he and his men were not present at the Battle of Okehazama where Yoshimoto was killed in Nobunaga's surprise assault.