On 19 December 1944 he was ordered with his heavy machine-gun squad to the support of an infantry company attacking the outer defenses of the Siegfried line near Berg, Germany. For eight hours he maintained a position made almost untenable by the density of artillery and mortar fire concentrated upon it and the proximity of enemy troops who threw hand grenades into the emplacement. While all other members of his squad became casualties, he remained at his gun. When he ran out of ammunition, he fearlessly dashed across bullet-swept, open terrain to secure a new supply from a disabled friendly tank. A fierce barrage pierced the water jacket of his gun, but he continued to fire until the weapon overheated and jammed. Instead of withdrawing, he crawled 50 yards across coverless ground to another of his company's machine guns which had been silenced when its entire crew was killed. He continued to man this gun, giving support vitally needed by the infantry. At one time he came under direct fire from a hostile tank, which shot the glove from his hand with an armor-piercing shell but could not drive him from his position or stop his shooting. When the American forces were ordered to retire to their original positions, he remained at his gun, giving the only covering fire. Finally withdrawing, he cradled the heavy weapon in his left arm, slung a belt of ammunition over his shoulder, and walked to the rear, loosing small bursts at the enemy as he went. One hundred yards from safety, he was struck in the leg by a mortar shell; but, with a supreme effort, he crawled the remaining distance, dragging along the gun which had served him and his comrades so well. By his remarkable perseverance, indomitable courage, and heroic devotion to his task in the face of devastating fire, TSgt. Gerstung gave his fellow soldiers powerful support in their encounter with formidable enemy forces.