Luftwaffe units committed to battle after the D-Day landings suffered further catastrophic losses. In the ten weeks of action following D-Day, JG 1 lost 106 aircraft (41 in air combat) and 30 pilots, for just 32 claims. Many experienced and irreplaceable "Experte" were killed during this time. Karl-Heinz Weber, "Gruppenkommandeur" of III./JG 1 (136 claims) was killed in action against Polish Wing Mustangs on 7 June 1944, north of Paris, while on 17 June 1944, "Leutnant" 'Toni' Piffer (35 claims) was shot down and killed in aerial combat with USAAF fighters over La Cordonnerie. Piffer had the hollow distinction of being awarded the Knight's Cross posthumously on 20 October, over four months after his death. His total included 26 four-engine bombers. JG 1 and JG 11 had fought side by side through their divisions campaign in Normandy, lost 100 pilots between them. The oil famine began to bite in July, and in that months' first week the bomber groups were withdrawn to Germany and disbanded. On 11 August a general order came through to curtail the use of fuel for operations against heavy bombers only. Small reinforcements were sent to cover the German army as it was routed and the front in Normandy collapsed, but the 75 single-engined fighters remaining made no difference. The remnants of the Luftwaffe began to retreat from France. ULTRA intercepts from 18 August 1944 noted an order to withdraw JG 1 from Normandy along with the "Jagdivision" 5 which had been responsible for operations west of the Seine. JG 27 and "Jagdivision" 4 replaced them.