During tank fighting in the Normandy campaign, the M10's 3-inch gun was proven to be ineffective against the thick frontal armor of the German Panther tank. On 6 July 1944, Eisenhower's headquarters requested that all M10 battalions be converted to the new M36 as soon as possible. On 10 July 1944, the 899th Tank Destroyer Battalion blunted a German counterattack by the Panzer Lehr Division near Le Dézert and destroyed 12 Panthers, one Panzer IV, and one Sturmgeschütz III in a fierce two-day battle, most of it taking place at ranges of less than 200 m. Due to the initial shock of encountering heavy German tanks, further changes were made in the tank destroyer force in late September 1944. American officials requested that of the 52 battalions then committed to the European theater, 20 be converted to the M36, 20 retain the M10 or M18 at the discretion of their commanders, and the 12 towed battalions be re-equipped with the (then-prototype) T5 90 mm towed gun. By October 1944, the improved 90 mm Gun Motor Carriage M36 began to arrive in Europe, and mostly replaced the M10 by the end of the war. The plans to retain any towed battalions at all were canceled after their generally poor performance and high losses in 1944, especially during the Battle of the Bulge.