During the following two years, Agase served on active duty in the war. He participated in the battles of Iwo Jima and Okinawa, where he received a Purple Heart after he was wounded in action. He rose to the rank of first lieutenant. Agase returned to Illinois in 1946 and rejoined a Fightining Illini team that posted an 8–2 record and was ranked fifth in the nation in the AP Poll at season's end. Illinois beat the UCLA Bruins in the 1947 Rose Bowl after the season. Agase was named an All-American for a third time, and received the Chicago Tribune Silver Football as the most valuable player in the Big Ten.