page_title: 1st Anti-Aircraft Division (United Kingdom)
section_title: The Blitz
hierarchical_section_title: 1st Anti-Aircraft Division (United Kingdom) / The Blitz
caption_attribution_description: IWM caption&#160;: Royal Artillerymen at a 'Z' Battery load 4-inch anti-aircraft rockets into a mobile launcher. Comment&#160;: These are actually 3-inch rockets.
context_page_description: The 1st Anti-Aircraft Division was an Air Defence formation of the British Army before and during the early years of World War II. It defended London during the Battle of Britain and The Blitz.
context_section_description: By 30 September, when the Battle of Britain was effectively over and the Luftwaffe had switched to night raids over London (The Blitz), by now the 1st AA Division had 233 HAA guns, 60 LAA guns, 161 LMGs and 242 searchlights covering the London IAZ, together with 36 HAA guns defending Slough, Langley, Weybridge and airfields.
  In the absence of inland radar coverage, the 1st AA Division's Chief Signals Officer, Lt-Col G.C. Wickens, devised a system of 14 fixed base-lines of sound locators to detect night raids approaching the IAZ. These were linked by automatic telephone equipment to the Brompton operations room, where the angular plots were resolved to indicate grid squares where the HAA guns in range could fire an unseen barrage. This 'Fixed Azimuth' system came into action in June 1940, in time for the opening of the night Blitz on London. It was later replaced as searchlight control (SLC) and gunlaying (GL) radar systems were introduced.
  However, the performance of the AA defences in the early weeks of the Blitz was poor. AA Command moved 108 HAA guns to the IAZ from other divisions, and arranged 'fighter nights' when the guns remained silent and RAF night fighters were allowed to operate over London with the searchlights. GL radar, modern sound-locators and larger (150 cm) searchlights were introduced as rapidly as possible. From September 1940, rocket projectors (Z Batteries) were introduced, equipped with rocket projectiles, and by February 1941, SLC began to be issued. The number of raiders shot down steadily increased until mid-May 1941, when the Luftwaffe scaled down its attacks. During 1941 increasing numbers of women of the Auxiliary Territorial Service (ATS) took over roles in AA Command. Where they were integrated into units these were designated 'Mixed' ('M').
caption: Loading a mobile Z Battery projector
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