Anti-aircraft warfare, counter-air, anti-air, AA guns, layered air defence or air defence forces is the battlespace response to aerial warfare, defined by NATO as "all measures designed to nullify or reduce the effectiveness of hostile air action". It includes surface based, subsurface, and air-based weapon systems, associated sensor systems, command and control arrangements, and passive measures. It may be used to protect naval, ground, and air forces in any location. However, for most countries, the main effort has tended to be homeland defence. NATO refers to airborne air defence as counter-air and naval air defence as anti-aircraft warfare. Missile defence is an extension of air defence, as are initiatives to adapt air defence to the task of intercepting any projectile in flight.
RAF Fighter Command was one of the commands of the Royal Air Force. It was formed in 1936 to allow more specialised control of fighter aircraft. It served throughout the Second World War. It earned near-immortal fame during the Battle of Britain in 1940, when the Few held off the Luftwaffe attack on Britain. The Command continued until 17 November 1943, when it was disbanded and the RAF fighter force was split into two categories; defence and attack. The defensive force became Air Defence of Great Britain (ADGB) and the offensive force became the RAF Second Tactical Air Force. Air Defence of Great Britain was renamed back to Fighter Command in October 1944 and continued to provide defensive patrols around Great Britain. It was disbanded for the second time in 1968, when it was subsumed into the new Strike Command.
The RAF Army Co-operation Command was a short-lived command of the Royal Air Force during the Second World War, comprising the army cooperation units of the RAF.
Anti-Aircraft 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.
The 1st Anti-Aircraft Division was an Air Defence formation of the British Army before and during the early years of the Second World War. It defended London during the Battle of Britain and The Blitz.
28th Anti-Aircraft Brigade was an air defence formation of the British Territorial Army created in 1925 to command anti-aircraft units in Kent and around the militarily important Medway Towns, which it defended during the Second World War. In 1940 the brigade was responsible for the defences on the south side of the Thames Estuary including the Royal Naval Dockyard at Chatham and the Port of Dover. The brigade was heavily engaged throughout the Battle of Britain, in the summer of 1940, and The Blitz, from autumn 1940 to spring 1941, operating a total of 70 heavy anti-aircraft (HAA) guns controlled from a gun operations room (GOR) at Chatham. During 1942 many of the brigade's experienced units were transferred to active theatres overseas. Increasingly the brigade included women of the Auxiliary Territorial Service (ATS).
The IV Home Counties (Howitzer) Brigade, Royal Field Artillery was a new volunteer unit formed in Kent as part of the Territorial Force (TF) in 1908. It saw active service on the Western Front during World War I and was reconstituted as medium artillery in the interwar years. Later it converted to anti-aircraft artillery, in which role it served in The Blitz, North Africa and Italy during World War II and continued under various designations until its disbandment in 1969.
The 73rd Searchlight Regiment was a volunteer air defence unit of Britain's Territorial Army (TA) from 1939 until 1955, at first as part of the Royal Engineers, later in the Royal Artillery. It served during the Battle of Britain and The Blitz.
The 4th Anti-Aircraft Division was an air defence formation of Britain's Territorial Army, created in the period of tension before the outbreak of the Second World War. It defended North West England during the Blitz.
43rd Anti-Aircraft Brigade was an air defence formation of Britain's Territorial Army (TA). Formed in 1938, it was responsible for protecting Teesside in North East England during the early part of the Second World War, and later defended South East England from V-1 flying bombs. It was reformed postwar and survived under different titles until 1961.
I Anti-Aircraft Corps was a high-level formation of Britain's Anti-Aircraft Command from 1940 to 1942. It defended Southern England and Wales during the Blitz and the middle years of the Second World War.
II Anti-Aircraft Corps was a high-level formation of Britain's Anti-Aircraft Command from 1940 to 1942. It defended the Midlands and North West of England and Wales during the Blitz and the middle years of the Second World War.
III Anti-Aircraft Corps was a high-level formation of Britain's Anti-Aircraft Command from 1940 to 1942. It defended Scotland, Northern Ireland and North East England during the Blitz and the middle years of the Second World War.
No. 85 Group was a Group of the Royal Air Force (RAF) during World War II. It was responsible for airfield construction and the air defence of the beachhead bases during the Allied invasion of Normandy in 1944 and the subsequent campaign.
6th Anti-Aircraft Brigade was an air defence formation of the British Army formed during the Second World War. It served in the disastrous Norwegian Campaign in 1940 and then defended East Anglia during the Battle of Britain and The Blitz. It was reorganised to take part in the invasion of Normandy, but instead was diverted to defending Southern England against V-1 flying bombs. It was briefly recreated in the postwar Regular Army.
228th (Edinburgh) Heavy Anti-Aircraft Battery, Royal Artillery was a Scottish air defence unit of Britain's Territorial Army (TA) formed around Edinburgh during the period of international tension leading up to the outbreak of World War II. It defended Eastern Scotland during the early part of the war and then served in the defence of Gibraltar. Its successor unit served in the postwar TA as air defence artillery and as engineers until 1999.
79th Searchlight Regiment was an air defence unit of Britain's Royal Artillery during World War II. It protected London and South East England as part of Anti-Aircraft Command from the Blitz of 1940 until Operation Diver in 1944, after which it was disbanded.
The 132nd Light Anti-Aircraft Regiment, was an air defence unit of the British Army's Royal Artillery during World War II. The regiment was formed in March 1942 from the short-lived 85th Searchlight Regiment, Royal Artillery which had only been raised in the previous year as part of the rapid expansion of Anti-Aircraft Command. It served in Home Defence throughout the war, until disbandment in 1945.
The 90th Searchlight Regiment, Royal Artillery, was a short-lived air defence unit of the British Army during World War II. It served in Anti-Aircraft Command from 1941 to 1943, mainly in Northern Ireland, and never deployed overseas.
57 Signal Squadron and its predecessors were units of the Royal Corps of Signals in Britain's Territorial Army and Army Reserve from 1939 to 2016. Its history began as part of Anti-Aircraft Command in World War II during the Battle of Britain and The Blitz, and continued postwar in various headquarters (HQ) and national communication roles.
United Kingdom 
Royal Air Force 