Increasing concern during the 1930s about the threat of air attack led to large numbers of units of the part-time Territorial Army (TA) being converted to anti-aircraft (AA) gun and searchlight roles in the Royal Artillery (RA) and Royal Engineers (RE), and higher formations became necessary to control them. One such formation was 4 AA Division, raised on 1 September 1938 in Western Command, with its Headquarters at Chester. The first General Officer Commanding (GOC) was Maj-Gen Hugh Martin.
The AA Divisions were unlike field formations: they were established to organise training and later exercise operational command in the static conditions of home defence, but relied entirely on the Home Forces commands for logistic support, supplies, and heavy repairs. They came under the operational control of RAF Fighter Command.
4 AA Division was initially responsible for the industrial areas of the North West and West Midlands of England and North and South Wales. At first it consisted of two brigades: the existing Liverpool-based 33rd (Western) AA Bde transferred from 2 AA Division and the newly formed 34th (South Midland) AA Bde based at Coventry. Shortly afterwards, 44th AA Bde was formed at Manchester. The division came under the control of Anti-Aircraft Command when that was formed in April 1939.
The deterioration in international relations led to a partial mobilisation in June 1939, and a proportion of TA AA units manned their war stations under a rotation system known as 'Couverture'. Full mobilisation of AA Command came in August 1939, ahead of the declaration of war on 3 September 1939. Two new brigades, 53rd (Light) AA Bde composed of Light AA (LAA) units, and 54th, composed of searchlight units, were in the process of formation in 4 AA Division as mobilisation proceeded.
On mobilisation in August 1939, the division was composed as follows:
33rd (Western) Anti-Aircraft Brigade – HQ at Liverpool70th (3rd West Lancashire) AA Regiment, RA – Heavy Anti-Aircraft (HAA) unit formed in 1937 at Aigburth, Liverpool, by conversion of 89th (3rd West Lancashire) Field Brigade, RA81st AA Regiment, RA – HAA unit formed in 1936 at Stalybridge and Stockport by conversion of 60th (Cheshire & Shropshire) Medium Brigade, RA93rd AA Regiment, RA – new HAA unit raised in 1939 in Birkenhead and Chester38th (The King's Regiment) AA Battalion, RE – Searchlight unit formed in 1936 at Liverpool by conversion of 6th (Rifles) Bn King's Regiment (Liverpool)4th Battalion, The Loyal Regiment (North Lancashire) (62nd Searchlight Regiment, RA) – infantry battalion based at Preston converted into a searchlight unit in 193833rd AA Brigade Company Royal Army Service Corps34th (South Midland) Anti-Aircraft Brigade – HQ at Coventry69th (Royal Warwickshire Regiment) AA Regiment, RA – HAA unit formed at Birmingham in 1936 by conversion of 6th Battalion Royal Warwickshire Regiment73rd AA Regiment, RA – HAA unit raised at Wolverhampton and West Bromwich in 1938 from batteries drawn from 62nd (North Midland) Field Brigade, RA and 51st (Midland) Medium Brigade, RA95th (Birmingham) AA Regiment, RA – newly raised in April 1939, with one battery from 73 AA Regiment34th AA Brigade Company, RASC44th Anti-Aircraft Brigade – HQ at Manchester65th (The Manchester Regiment) AA Regiment, RA – HAA unit formed at Hulme in 1936 by conversion of 6th/7th Battalion Manchester Regiment39th (The Lancashire Fusiliers) AA Battalion, RE – Searchlight unit formed at Salford in 1936 by conversion of 7th Bn Lancashire Fusiliers71st (East Lancashire) Searchlight Regiment, RA – new searchlight unit raised in Manchester in 193844th AA Brigade Company, RASC53rd Light Anti-Aircraft Brigade – Forming at Chester15th (Isle of Man) LAA Regiment, RA – at Douglas, Isle of Man21st LAA Regiment, RA – at Liverpool25th LAA Regiment, RA – at Liverpool33rd LAA Regiment, RA – at Liverpool53rd AA Brigade Company, RASC54th Anti-Aircraft Brigade – forming at Sutton Coldfield41st (5th North Staffordshire Regiment) AA Battalion, RE – infantry battalion at Stoke-on-Trent converted to searchlights in 193645th (The Royal Warwickshire Regiment) AA Battalion, RE – infantry battalion at Birmingham converted to searchlights in 193659th (Warwickshire) Searchlight Regiment, RA – new unit formed from a battery of 45 AA Bn in 193861st (South Lancashire Regiment) Searchlight Regiment, RA – infantry battalion at St Helens converted to searchlights in 193854th AA Brigade Company, RASC4th AA Divisional Signals, Royal Corps of Signals – formed at liverpool, later at Chester, from a cadre provided by 55th (West Lancashire) Divisional Signals4 AA Divisional Royal Army Service Corps – at Chester182 and 913 Companies4 AA Divisional Company, Royal Army Medical Corps – at Manchester4th AA Divisional Workshop, Royal Army Ordnance Corps – RAOC Workshop companies became part of the new Royal Electrical and Mechanical Engineers (REME) during 1942At this point the division had a strength of 92 HAA guns (3-inch, 3.7-inch and 4.5-inch) while in the LAA role there were 26 3-inch, 13 2-pounder 'pom-pom' and 40 mm Bofors guns, and 469 light machine guns (LMGs), together with 244 searchlights. The HAA guns were deployed in the defended areas as follows:
Liverpool – 19 (plus 3 out of action)Manchester – 12 (plus 10 out of action)Birmingham – 20 (plus 4 out of action)Coventry –12Cardiff – 6 (plus 2 out of action)Newport – 4During the period of the Phoney War, the AA defences of NW England were not tested in action, and the time was spent in equipping and training the TA units. AA Command also had to provide equipment and units to the British Expeditionary Force assembling in France. From 4 AA Division, 73rd AA Regiment went to France in November 1939 where it joined 12th Anti-Aircraft Brigade providing AA cover for the airfields of the RAF's Advanced Air Striking Force. In January 1940, Maj-Gen Martin went to command the AA defences of the BEF. He was replaced by Maj-Gen Charles Cadell, recently returned from commanding the AA defences of Malaya.
In the summer of 1940, all AA units equipped with 3-inch or heavier guns were designated as Heavy AA (HAA) regiments to distinguish them from the newer LAA units. Also, in August the AA battalions were transferred from the RE to the RA, which designated them searchlight regiments.
At the start of the Battle of Britain, in July 1940, 4 AA Division's guns were deployed as follows:
Liverpool – 52Manchester – 20Crewe – 8Birmingham – 64Coventry – 44RAF Ringway – 4Vital Points – 52 (mainly LAA)In September 1940, 4 AA Division formed 4th AA Z Regiment to command the new short-range rocket weapons known as Z Batteries. Also in September 1940, RAF Fighter Command created a new HQ (No. 9 Group RAF) to cover NW England, and henceforth 4 AA Division cooperated with it.
As the Battle of Britain fought over southern England in the summer of 1940 developed into the night bombing of the Blitz in the autumn, AA Command continued to expand. In November a new division was formed by splitting 34 and 54 AA Brigades off from 4 AA Division to create 11 AA Division, which took over responsibility for the West Midlands, while 9 AA Division took over South Wales. At the same time, 4 AA Division came under the control of a newly formed II AA Corps.
The cities of NW England were heavily bombed during the winter of 1940–41 (the Liverpool Blitz and Manchester Blitz) and 'the actions fought [by the AA batteries] were as violent, dangerous and prolonged as any in the field'. 'On an HAA 4.5-inch position of 44th AA Brigade in Manchester, the power rammer on one gun failed. One Gunner loaded 127 of the 86-lb [40 kg] rounds himself in eleven hours of action, despite injuries to his fingers'.
The wide Mersey Estuary left a gap in the Liverpool defences that could not be fully covered by AA guns, and by mid-1941 AA Command had begun constructing three Maunsell Forts in the estuary on which to mount AA guns.
During the winter of 1940–41, the division was composed as follows:
33 AA Brigade – Liverpool103 HAA Regiment, RA – formed May 1940106 HAA Regiment, RA – formed August 194033 LAA Regiment, RA – as above42 LAA Regiment, RA – formed November 193965 LAA Regiment, RA (part) – formed November 194044 AA Brigade – Manchester98 HAA Regiment, RA – formed 1939115 HAA Regiment, R – formed November 194054 (Argyll & Sutherland Highlanders) LAA Regiment, RA – formed 1938 by conversion of 9th (Dumbartonshire) Bn, Argyll and Sutherland Highlanders76 LAA Regiment, RA – formed February 194153 AA Brigade – North Midlands39 (Lancashire Fusiliers) S/L Regiment, RA – as above62 (The Loyals) S/L Regiment, RA – as above71 (East Lancashire) S/L Regiment, RA – as above92 S/L Regiment, RA – formed May 19414 AA Z Regiment, RA – as above13 AA Z Regiment, RA – 'formed August 1941The night raids continued into the following Spring, during which period Liverpool and its docks along the Mersey became the most heavily bombed area of Britain outside London, with particularly heavy attacks in December 1940 (the Christmas Blitz); in April 1941; and again the following month (the May Blitz).
The main Blitz ended in May 1941, but occasional raids continued on Manchester and Liverpool. Newly formed AA units joined the division, the HAA units increasingly being 'mixed' ones into which women of the Auxiliary Territorial Service were integrated. At the same time, experienced units were posted away for service overseas. This led to a continual turnover of units, which accelerated in 1942 with the preparations for Operation Torch and the need to transfer AA units from North West England to counter the Baedeker Blitz and the Luftwaffe's hit-and-run attacks against South Coast towns.
During this period the division was composed as follows:
33 AA Brigade1 HAA Rgt – Regular regiment, transferred from 1st AA Bde at Crewe; to Northern Ireland July 194193 HAA Rgt – as above; to 44 AA Bde July 194295 HAA Rgt – joined September 1942103 HAA Rgt – as above; left for mobile training May 1942107 HAA Rgt – new unit formed Autumn 1940, partly from 103 HAA Rgt; left April 1942117 HAA Rgt – joined autumn, to 70 AA Bde December 1941, returned May, left August 1942137 (Mixed) HAA Rgt – new unit formed November, joined December 1941, left September 1942149 (Mixed) HAA Rgt – new unit formed February, joined April 1942154 (Mixed) HAA Rgt – new unit formed March, joined May 194229 LAA Rgt – joined autumn 1941, left February 194233 LAA Rgt – as above; left autumn 194163 LAA Rgt – from 70 AA Bde August 194298 LAA Rgt – new unit formed December 1941, joined February, left May 1942134 LAA Rgt – new unit formed February, joined June, left August 19424 AA 'Z' Rgt – as above; to 70 AA Bde summer, rejoined autumn 1941, left August 194244 AA Brigade58 (Kent) HAA Rgt – joined February, left to join First Army for Operation Torch May 194270 HAA Rgt – as above; left for India February 194281 HAA Rgt – as above; rejoined from Orkney and Shetland Defences (OSDEF), June 1941; to 70 AA Bde summer 1941'93 HAA Rgt – as above; from 30 AA Bde July, left for Middle East August 194298 HAA Rgt – as above; left May 1942115 HAA Rgt – as above; to OSDEF June 1941151 (Mixed) HAA Rgt – new unit formed February, joined May, left July 194221 LAA Rgt – as above; left autumn 194139 LAA Rgt – joined summer; to 53 AA Bde autumn; rejoined December 1941; to 53 AA Bde July 194265 LAA Rgt – as above; left summer 194176 LAA Rgt – as above: to 70 AA Bde summer 194180 LAA Rgt – joined autumn 194188 LAA Rgt – joined May 194213 AA 'Z' Rgt – joined autumn 194153 AA Brigade39 LAA Rgt – as above; from 44 AA Bde autumn 1941 and again July 1942; left August 194239 S/L Rgt – as above; rejoined from OSDEF May 194162 S/L Rgt – as above71 S/L Rgt – as above; to OSDEF May 1941, returned January 194187th S/L Rgt – new unit formed January 1941; left May 194292 S/L Rgt – as above; to 70 AA Bde summer 194170 AA Brigade – new formation created June 194162 (Northumbrian) HAA Rgt – joined April, left for Operation Torch July 194281 HAA Rgt – as above; left for Middle East April 1942117 HAA Rgt – as above; from 33 AA Bde December 1941, returned May 1942131 (Mixed) HAA Rgt – joined August 194263 LAA Rgt – joined July, to 33 AA Bde August 194276 LAA Rgt – as above; left for Ceylon February 1942114 LAA Rgt – converted from 91 S/L Rgt January 1942; left for mobile training June 194292 S/L Rgt – as above4 AA 'Z' Rgt – as above; from 33 AA Bde summer, returned autumn 1941The increased sophistication of Operations Rooms and communications was reflected in the growth in signal units, which attained the following organisation by May 1942:
4 AA Division Mixed Signal Unit HQ, RCSHQ No 1 Company4 AA Division Mixed Signal Office Section321 AA Gun Operations Room Mixed Signal Section323 AA Gun Operations Room Mixed Signal Section325 AA Gun Operations Room Mixed Signal Section70 AA Brigade Signal Office Mixed Sub-Section10 AA Line Maintenance SectionHQ No 2 Company406 AA Gun Operations Room Mixed Signal Section18 AA Sub-Gun Operations Room Mixed Signal Sub-Section19 AA Sub-Gun Operations Room Mixed Signal Sub-Section20 AA Sub-Gun Operations Room Mixed Signal Sub-Section21 AA Sub-Gun Operations Room Mixed Signal Sub-Section33 AA Brigade Signal Office Mixed Sub-Section330 AA Gun Operations Room Mixed Signal Section44 AA Brigade Signal Office Mixed Sub-Section53 AA Brigade Signal Office Mixed Sub-Section117 RAF Fighter Sector Sub-Section11 AA Line Maintenance Section12 AA Line Maintenance Section34 AA Sub-Gun Operations Room Mixed Signal Sub-Section4 AA Div Radio Maintenance Company, RAOC (later REME)Disbandment
At the end of September 1942, AA Command disbanded the AA Corps and Divisions and replaced them with new AA Groups, whose areas of responsibility coincided with the Groups of RAF Fighter Command. 4 AA Division's responsibilities were taken over by 4 AA Group, with its HQ at Preston, which covered NW England and N Wales and operated with 9 Group RAF. 4 AA Divisional Signals became 4 AA Group Signals on 21 October 1942 4 AA Group in turn was disbanded in November 1944.
General Officer Commanding
The following officers commanded 4th AA Division:
Major-General Hugh Martin (1 September 1939–9 January 1940)Major-General Robert Pargiter (10 January–27 May 1940)Major-General Charles Cadell (28 May–13 February 1942)Major-General Osmund Frith (14 February–30 September 1942)
