Citation... For conspicuous gallantry and intrepidity at the risk of his life above and beyond the call of duty in action involving actual conflict with the enemy, on 1 February 1944 near Cisterna di Littoria, Italy. When a heavy German counterattack was launched against his battalion, Pfc. Knappenberger crawled to an exposed knoll and went into position with his automatic rifle. An enemy machinegun 85 yards away opened fire, and bullets struck within 6 inches of him. Rising to a kneeling position, Pfc. Knappenberger opened fire on the hostile crew, knocked out the gun, killed 2 members of the crew, and wounded the third.

While he fired at this hostile position, 2 Germans crawled to a point within 20 yards of the knoll and threw potato-masher grenades at him, but Pfc. Knappenberger killed them both with 1 burst from his automatic rifle. Later, a second machinegun opened fire upon his exposed position from a distance of 100 yards, and this weapon also was silenced by his well-aimed shots. Shortly thereafter, an enemy 20mm. antiaircraft gun directed fire at him, and again Pfc. Knappenberger returned fire to wound 1 member of the hostile crew. Under tank and artillery shellfire, with shells bursting within 15 yards of him, he held his precarious position and fired at all enemy infantrymen armed with machine pistols and machineguns which he could locate. When his ammunition supply became exhausted, he crawled 15 yards forward through steady machinegun fire, removed rifle clips from the belt of a casualty, returned to his position and resumed firing to repel an assaulting German platoon armed with automatic weapons. Finally, his ammunition supply being completely exhausted, he rejoined his company. Pfc. Knappenberger's intrepid action disrupted the enemy attack for over 2 hours.