Some damaged Allied bombers returning from raids over Italy and Germany would intentionally violate Swiss airspace, preferring internment by the Swiss to becoming prisoners of war. Over a hundred Allied aircraft and their crews were interned in this manner. They were subsequently put up in various ski resorts that had been emptied from lack of tourists due to the war and held until hostilities ended. At least 940 American airmen attempted to escape into France after the Allied invasion of Normandy in June 1944 but Swiss authorities intercepted 183 internees. Over 160 of these airmen were incarcerated in a Swiss prison camp known as Wauwilermoos, which was located near Lucerne and commanded by André Béguin, a pro-Nazi Swiss officer. The American internees remained in Wauwilermoos until November 1944 when the U.S. State Department lodged protests against the Swiss government and eventually secured their release. The American military attaché in Bern warned Marcel Pilet-Golaz, Swiss foreign minister in 1944, that "the mistreatment inflicted on US aviators could lead to 'navigation errors' during bombing raids over Germany".