Anti-Aircraft Command (AA Command, or "Ack-Ack Command") was a British Army command of the Second World War that controlled the Territorial Army anti-aircraft artillery and searchlight formations and units defending the United Kingdom. Origin The formation of a Command-level body of anti-aircraft defences had been announced in 1938, but Anti-Aircraft Command was not formed until 1 April 1939 under General Sir Alan Brooke, who had been commander of Anti-Aircraft Corps. He then passed control to Sir Frederick Pile, who would remain in command until the end of the war. AA Command was under the operational direction of RAF Fighter Command as part of Air Defence of Great Britain, and occupied a headquarters known as Glenthorn in the grounds of Bentley Priory, home of Fighter Command. The majority of AA Command's guns and searchlights were operated by Territorial Army units. Some Regular Army units joined after they returned from the Dunkirk evacuation. Later, as the war progressed, Regulars and TA were freed up for overseas service by the use of men of the Home Guard (loading and firing the guns) and women of the Auxiliary Territorial Service (handling ammunition and operating gun directors). Organisation Divisional Divisions under the command were: 1st Anti-Aircraft Division – Existing division at start of the war, headquartered in Uxbridge. 2nd Anti-Aircraft Division – Existing division at the start of the war, headquartered at RAF Hucknall, Nottinghamshire. 3rd Anti-Aircraft Division – Existing division at the start of the war, headquartered in Edinburgh. 4th Anti-Aircraft Division – Existing division at the start of the war, headquartered in Chester. 5th Anti-Aircraft Division – Existing division at the start of the war, headquartered in Reading. 6th Anti-Aircraft Division – Existing division at the start of the war, headquartered in Uxbridge. 7th Anti-Aircraft Division – Existing division at the start of the war, headquartered in Newcastle upon Tyne. 8th Anti-Aircraft Division – Formed November 1940 covering South West England, headquartered in Bristol. 9th Anti-Aircraft Division – Formed November 1940 covering South Wales, headquartered in Cardiff. 10th Anti-Aircraft Division – Formed November 1940 covering Yorkshire and the Humber Estuary. 11th Anti-Aircraft Division – Formed November 1940 covering the West and Central Midlands. 12th Anti-Aircraft Division – Formed November 1940 covering southwestern Scotland. AA Command was also responsible for the Orkney and Shetland Defences (OSDEF). Corps At the end of 1940, the Command created three Corps to supervise this expanding organisation: I Anti-Aircraft