In the Luftwaffe of Nazi Germany during World War II, a Flak division (German: Flak-Division) was a division-sized military formation that was officially tasked with the conduct of anti-aircraft warfare, often against the Allied strategic bombing campaigns.
[2]: 96 Besides the Flak Corps and the Flak Detachments, air defense in the German homeland was handled by the Air Defense Commands (Luftverteidigungskommandos), of which 6 had been formed by the beginning of war in September 1939 (Berlin, Leipzig, Hamburg, Düsseldorf, Frankfurt/Main, Hanover), which were joined by 5 more throughout the years of 1940 and 1941 (Cologne, German-occupied Denmark, German-occupied France, Romanian oilfields, Fortress Flak).
[1]: 364 These eleven air defense commands were collectively renamed on 1 September 1941 to become the 1st through 11th Flak Divisions.
[3]: 221 In summer of 1942, the German casualties on the Eastern Front forced military reorganizations.
Several of the experienced Flak Divisions at home were now to be freed up for frontline action through the formation of new units.
[1]: 365 The rapid Allied advances of June and July 1944 caused panicked reorganizations.