At UCLA, Compton participated in ROTC under Cadet Commander John Singlaub. In December 1943, he joined the Army and was assigned to E Company, 2nd Battalion, 506th Parachute Infantry Regiment in the 101st Airborne Division before Operation Overlord. During the company's action at Brécourt Manor, Compton and others, under the leadership of Lieutenant Richard Winters, assaulted a German battery of four 105 mm howitzers firing on Utah Beach, disabling the guns and routing the enemy. Compton was awarded the Silver Star for his action in disabling the guns. Episode two ("Day of Days") of the HBO miniseries "Band of Brothers" depicts this assault. During the battle, he threw a grenade that was said to have no arc and hit the German soldier on the back of the helmet.