When Japanese American soldiers were allowed to reenter active service in March 1943, Munemori volunteered to be part of the all-"Nisei" 442nd Regimental Combat Team. This segregated army unit was made up entirely of Japanese Americans, with most initial recruits coming from Hawaii. The unit began as the 100th Infantry, initially listed as a separate battalion, and fought as part of the 133rd Infantry Regiment within the 34th Infantry Division. After the Allied capture of Rome, the battalion withdrew from the front and became the 1st Battalion of the 442nd RCT. Munemori was sent to Camp Shelby in January 1944 and, after completing his combat training three months later, joined the 100th Battalion in the European Theater. Fighting in Italy and France, he participated in the rescue of the Lost Battalion before arriving on the Gothic Line, where he was killed in action.