For conspicuous gallantry and intrepidity at the risk of his life above and beyond the call of duty as tank commander serving with the 2d Battalion, 6th Marines, 2d Marine Division, during action against enemy Japanese forces on Saipan, Mariana Islands, on 8 July 1944. Advancing with his tank a few yards ahead of the infantry in support of a vigorous attack on hostile positions, Sgt. Timmerman maintained steady fire from his antiaircraft sky-mount machine gun until progress was impeded by a series of enemy trenches and pillboxes. Observing a target of opportunity, he immediately ordered the tank stopped and, mindful of the danger from the muzzle blast as he prepared to open fire with the 75-mm, fearlessly stood up in the exposed turret and ordered the infantry to hit the deck. Quick to act, as a grenade, hurled by the Japanese, was about to drop into the open turret hatch, Sgt. Timmerman unhesitatingly blocked the opening with his body, holding the grenade against his chest and taking the brunt of the explosion. His exceptional valor and loyalty in saving his men at the cost of his own life reflect the highest credit upon Sgt. Timmerman and the U.S. Naval Service. He gallantly gave his life in the service of his country.