In July 1943, the division took part in the Allied invasion of Sicily, codenamed Operation Husky, still under the command of Major General Allen. Lieutenant General George S. Patton, commanding the U.S. Seventh Army, specifically requested the division as part of his forces for the invasion of Sicily. It was still assigned to the II Corps. In Sicily the 1st Division saw heavy action when making amphibious landings opposed by Italian and German tanks at the Battle of Gela. The 1st Division then moved up through the center of Sicily, slogging it out through the mountains along with the 45th Infantry Division. In these mountains, the division saw some of the heaviest fighting in the entire Sicilian campaign at the Battle of Troina; some units losing more than half their strength in assaulting the mountain town. On 7 August 1943, Major General Allen was relieved of his command by Lieutenant General Omar Bradley, then commanding the II Corps. Allen was replaced by Major General Clarence R. Huebner who was, like Allen, a decorated veteran of World War I who had served with the 1st Infantry Division throughout the war.