The most significant employment of tank destroyers in Normandy was in early August, at the Battle of Mortain, where the 823rd Tank Destroyer Battalion (towed 3-inch guns) was on the defensive alongside the 30th Infantry Division. The division, which was in temporary positions and not prepared for a defensive engagement, was attacked by elements of four panzer divisions on 6 August, under heavy fog. The 823rd put up a strong defense—knocking out fourteen tanks—but took heavy losses, being mostly overrun and losing eleven guns. This served to reinforce misgivings about the effectiveness of the towed units, and a report delivered to the Pentagon in December recommended they be phased out in favor of self-propelled units.