Fall Gelb began on 10 May 1940. Sperrle's air fleet engaged in operations supporting "Generalfeldmarschall" Gerd von Rundstedt and Army Group A in the Battle of Belgium and Battle of France, as well as Army Group C. Sperrle's counter-air campaign started badly, reflecting poor photographic interpretation of targets, though he later claimed Luftflotte 3's operations were decisive in achieving air superiority. Kesselring's Luftflotte 2 achieved far greater success. Only 29 of the 42 airfields bombed were being used. Three RAF Advanced Air Striking Force bases were struck. Sperrle's men claimed 240 to 490 aircraft destroyed, mostly "in hangars"—Allied losses were actually 40 first-line aircraft. The penalty for failing to neutralise Allied fighter units cost Sperrle 39 aircraft. Loerzer lost 23—the highest loss of any air corps on the day.