1st Anti-Aircraft Division (United Kingdom)

1st Anti-Aircraft Division (1 AA 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 Blitz.

Origin
1 AA Division was organised on 15 December at Hillingdon House, RAF Uxbridge (at that time the headquarters of the Royal Observer Corps). The headquarters of the division was formed by converting 47th (1/2nd London) Division, whose General Officer Commanding, Major-General R.H.D. Thomson, continued as GOC of the new formation. Responsible to London District, the Division's role was to command the growing number of Territorial Army (TA) anti-aircraft gun and searchlight units around London (2 AA Division was in formed in 1936 to cover the rest of the country).

Order of Battle 1935
1 AA Division was initially composed of the following formations and units:
 * GOC: Major-General R.H.D. Thomson
 * 26th (London) AA Group organised 16 December 1935 at the Duke of York's Headquarters, Chelsea
 * 51st (London) Anti-Aircraft Brigade, Royal Artillery (TA) – AA guns
 * 52nd (London) Anti-Aircraft Brigade, RA (TA) – AA guns
 * 53rd (City of London) Anti-Aircraft Brigade, RA (TA) – AA guns
 * 54th (City of London) Anti-Aircraft Brigade, RA (TA) – AA guns
 * 26th (London) Anti-Aircraft Battalion (London Electrical Engineers), Royal Engineers (TA) – searchlights
 * 27th (London) Anti-Aircraft Battalion (London Electrical Engineers), RE (TA) – searchlights


 * 27th (Home Counties) AA Group organised 15 December 1935 at RAF Kenley, Surrey
 * 60th (City of London) Anti-Aircraft Brigade, RA (TA) – AA guns
 * 30th (Surrey) Anti-Aircraft Battalion,RE (TA) – searchlights
 * 31st (City of London Rifles) Anti-Aircraft Battalion, RE (TA) – searchlights
 * 34th (The Queen's Own Royal West Kent) Anti-Aircraft Battalion, RE (TA) – searchlights
 * 35th (First Surrey Rifles) Anti-Aircraft Battalion, RE (TA) – searchlights


 * 28th (Thames and Medway) AA Group
 * 55th (Kent) Anti-Aircraft Brigade, RA (TA) – AA guns
 * 58th (Kent) Anti-Aircraft Brigade, RA (TA) – AA guns
 * 61st (Finsbury Rifles) Anti-Aircraft Brigade, RA (TA) – AA guns
 * 29th (Kent) Anti-Aircraft Battalion, RE (TA) – searchlights
 * 32nd (7th City of London) Anti-Aircraft Battalion, RE (TA) – searchlights


 * 29th (East Anglian) AA Group organised January 1936 at RAF North Weald, Essex
 * 59th (The Essex Regiment) Anti-Aircraft Brigade, RA (TA) – AA guns
 * 28th (Essex) Anti-Aircraft Battalion, RE (TA) – searchlights
 * 33rd (St Pancras) Anti-Aircraft Battalion, RE (TA) – searchlights
 * 36th (Middlesex) Anti-Aircraft Battalion, RE (TA) – searchlights


 * 1st Anti-Aircraft Divisional Signals, Royal Corps of Signals, Regency Street, London SW1
 * 1st Anti-Aircraft Divisional Royal Army Service Corps, Crescent Road, Plumstead

In 1938 the Royal Artillery replaced the unit designation 'Brigade' by 'Regiment', which allowed the AA Groups to take the more usual formation title of Brigades.

Outbreak of War
During the period of tension leading to the Munich crisis and eventually the outbreak of World War II, the Territorial Army grew enormously, and existing TA infantry battalions continued to be converted to AA regiments. The existing divisions and brigades were expanded, and the whole AA defence of the United Kingdom was taken over by Anti-Aircraft Command on 1 April 1939. When the UK declared war on 3 September 1939, 1 AA Division had the following composition:

General Officer Commanding: Major-General F.L.M. Crossman, DSO, MC HQ: Hillingdon House, RAF Uxbridge


 * 26th (London) Anti-Aircraft Brigade, Brompton Road, London SW3 – heavy AA guns
 * 53rd (City of London) Anti-Aircraft Regiment, RA (TA)
 * 86th (Honourable Artillery Company) Anti-Aircraft Regiment, RA (TA)
 * 88th Anti-Aircraft Regiment, RA (TA)


 * 38th Light Anti-Aircraft Brigade, organised 28 September 1938 at Duke of York's Headquarters, Chelsea – searchlights
 * 26th (London Electrical Engineers) Anti-Aircraft Battalion, RE (TA)
 * 27th (London Electrical Engineers) Anti-Aircraft Battalion, RE (TA)
 * 75th (Middlesex) Searchlight Regiment, RA (TA)


 * 48th Anti-Aircraft Brigade, organised 28 August 1939 at Lewisham – heavy AA guns
 * 54th (City of London) Anti-Aircraft Regiment, RA (TA)
 * 60th (City of London) Anti-Aircraft Regiment, RA (TA)
 * 97th (London Scottish) Anti-Aircraft Regiment, RA (TA)
 * 99th Anti-Aircraft Regiment, RA (TA)


 * 49th Anti-Aircraft Brigade, organised 28 August 1939 at Lower Belgrave Street, London SW1 – heavy AA guns
 * 51st (London) Anti-Aircraft Regiment, RA (TA)
 * 52nd (London) Anti-Aircraft Regiment, RA (TA)
 * 84th (Middlesex, London Transport Anti-Aircraft Regiment), RA (TA)

The Blitz
In August 1940, during the Battle of Britain, the RE 'Anti-Aircraft' (searchlight) battalions became regiments of the RA. Royal Artillery AA units regiments were now designated Heavy Anti-Aircraft (HAA), Light Anti-Aircraft (LAA), or Searchlight (S/L) regiments and batteries.

Towards the end of 1940, at the height of The Blitz, AA Command formed three AA Corps: 1st AA Division formed part of 1 AA Corps in Southern England. 1st AA Division was still covering London, and bore the brunt of the Luftwaffe attacks on the city. At this time its composition was as follows:


 * 26 AA Brigade: Brigadier S.K. Thorburn (12 November 1940–19 February 1943)
 * 4th HAA Regiment, RA – a Regular unit returned from Dunkirk
 * 52nd (London) HAA Regiment, RA (TA)
 * 119th HAA Regiment, RA (TA) – formed December 1940
 * 62nd LAA Regiment, RA (TA) – formed October 1940


 * 38 AA Brigade
 * 26th (London Electrical Engineers) S/L Regiment, RA (TA)
 * 35th (First Surrey Rifles) S/L Regiment, RA (TA)
 * 75th (Middlesex) S/L Regiment, RA (TA)
 * 79th S/L Regiment, RA (TA) – formed October 1940


 * 48 AA Brigade
 * 54th (City of London) HAA Regiment, RA (TA)
 * 97th (London Scottish) HAA Regiment, RA (TA)
 * 105th HAA Regiment, RA (TA) – formed September 1940


 * 49 AA Brigade
 * 84th (Middlesex, London Transport) HAA Regiment, RA (TA)
 * 109th HAA Regiment, RA (TA) – formed September 1940
 * 11th (City of London) LAA Regiment, RA (TA)
 * 36th LAA Regiment, RA (TA)
 * 42nd LAA Regiment, RA (TA)
 * 70th LAA Regiment, RA (TA) – formed January 1941

Between September 1940 and September 1941, 1st, 6th and 14th Anti-Aircraft Z Regiment, Royal Artillery were formed in 1 AA Division. Z Regiments were equipped with rocket launchers.

Disbandment
1 AA Division, like the other AA Corps and Divisions, was disbanded and replaced on 1 October 1942 by a new AA Group structure. London was covered by 1 AA Group.