How many combat aircraft did the Luftwaffe have in August 1939?

German military aviation strength stood at 4,201 operational aircraft, divided into 1,191 bombers, 361 dive bombers, 788 fighters, 431 heavy fighters and 488 transports. This fleet was organised into twenty-eight Geschwader, the wings into which the force was structured.

Ready for combat were nine fighter Jagdgeschwader, mostly equipped with the Messerschmitt Bf 109E; four Zerstörergeschwader equipped with the Messerschmitt Bf 110 heavy fighters; eleven bomber Kampfgeschwader, with the Heinkel He 111 and the Dornier Do 17Z as their main aircraft; and four dive-bomber Sturzkampfgeschwader. The Luftwaffe's Condor Legion had experimented with new doctrine and aircraft during the Spanish Civil War, where it helped Francisco Franco's Falange defeat the Republican forces; more than 20,000 German airmen gained combat experience there.

Albert Kesselring's Luftflotte 1 had 807 aircraft, plus 92 seaplanes from the Fliegerführer der Seeluftstreitkräfte. Alexander Löhr's Luftflotte 4 had 627 aircraft, reinforced by 30 Slovak aircraft. A further 406 fighters were held back for home defence, and there were also 333 reconnaissance aircraft. The Luftwaffe was an essential component of the Blitzkrieg battle plan and opened the invasion by bombing the defenceless town of Wieluń. German forces lost 285 aircraft from all causes, while another 279 suffered 10% or more damage and were either written off or required major repairs.