Once activated, the division remained in the United States for training and exercises. As the division, like all airborne units, was intended to be an elite formation, the training regime was extremely arduous. There were and towers built from which prospective airborne troops would jump off of to simulate landing by parachute, lengthy forced marches and practice jumps from transport aircraft; to pause in the doorway of an aircraft during a practice jump resulted in an automatic failure for the candidate. The resultant failure rate was accordingly high, but there was never a shortage of candidates, especially for the American divisions, as the rate of pay was much higher than that of an ordinary infantryman. As the division trained, a debate developed in the U.S. Army over whether the best use of airborne forces was "en masse" or as small compact units. On 9 July 1943, the first large-scale Allied airborne operation–the Allied invasion of Sicily (Operation Husky)–was carried out by elements of the U.S. 82nd Airborne Division and the British 1st Airborne Division. The Commanding General (CG) of the U.S. 11th Airborne Division, Major General Joseph May Swing, had been temporarily assigned to act as airborne advisor to General Dwight D. Eisenhower, the Supreme Allied Commander in the Mediterranean, for the invasion of Sicily, and had observed the airborne assault, which went badly. The U.S. 82nd Airborne Division had been deployed by both parachute and glider and had suffered high casualties, leading to a perception that it had failed to achieve many of its objectives.