4th Anti-Aircraft Brigade (4 AA Bde) was an air defence formation of the British Army during the Second World War. It was formed just before the Battle of France to protect the British Expeditionary Force's bases. After the Dunkirk evacuation it was reformed in Egypt as a mobile formation with the Western Desert Force. It played a distinguished part in the Defence of Tobruk in 1941, but its headquarters was captured in the Fall of Tobruk the following year. It was reconstituted as a training formation in Persia and Iraq Command for the rest of the war.
Battle of France As the British Expeditionary Force (BEF) in France expanded during the Phoney War period of early1940, new headquarters (HQs) were formed to control the various groups of anti-aircraft (AA) guns and searchlights (S/Ls) that were deployed to defend its field formations and base installations. 4th Anti-Aircraft Brigade HQ was formed at Camberley on 1 March 1940 and sent to France shortly before the Battle of France began on 10 May.Frederick, p. 1048.Routledge, pp. 114–6. It was commanded by Brigadier J.N. Slater.Farndale, Annex A.Farndale, Annex J.Slater at Generals of WWII.Photos of Slater at National Portrait Gallery. The major subordinate unit in the brigade was 4th AA Regiment, Royal Artillery, a Regular Army unit that had been based at Bulford Camp in Southern Command on the outbreak of war.Southern Command 3 September 1939 at Patriot Files. It had deployed to France in November 1939 equipped with 3-inch and 3.7-inch heavy anti-aircraft (HAA) guns. Since then it had moved between AA brigades and had suffered a constant turnover of batteries exchanged with other regiments, leading to complaints from the commanding officer (CO). The other units assigned to 4 AA Bde were two detached HAA batteries (from the part-time units of the Supplementary Reserve (SR) and Territorial Army (TA))and an independent light anti-aircraft (LAA) battery equipped with Bofors 40 mm guns. Coming directly under General Headquarters (GHQ) the brigade's role was to protect supply points and airfields behind the BEF's frontline forces.Ellis, Appendix I.Farndale. p. 13.Routledge, Table XVII, p. 125.
Order of Battle May 1940 During the Battle of France the brigade had the following composition:Routledge, Table XVIII, p. 126. 4th AA Rgt 1, 3, 27 AA Btys 21 AA Bty – from 8th (Belfast) AA Rgt (SR) 220 AA Bty – from 85th (Tees) AA Rgt (TA) 1 LAA Bty – independent 52nd (East Lancashire) LAA Rgt (TA) – joined after 4 AA Bde was attached to I Corps 154, 155, 156 LAA Btys
Following the German invasion of the Low Countries the BEF followed the pre-arranged Plan D and advanced into Belgium to take up defences along the Dyle. However the collapse of the Dutch forces and the German Army's rapid breakthrough in the Ardennes soon threatened the BEF's positions. It withdrew to the Escaut line under frequent air attack. 4th AA Regiment had been defending airfields around Aubigny and Arras, and then followed the BEF into Belgium, taking up positions around Tournai. Here it was in action for six days as the town was bombed by formations of Heinkel He 111s and Dornier Do 17s. On 18 May it was ordered back to Douai and Seclin airfields, the regimental HQ (RHQ) being bombed during the move. The next day it was ordered to move immediately to Templeuve between Orchies and Lille, a move involving great difficulty and much shooting.Farndale, pp. 43–4.Routledge, pp. 120–1.
Retreat to Dunkirk On 20 May Army Group A swung north to the English Channel and cut the BEF off. Forced to retire towards Dunkirk, the BEF's AA brigades were sucked into the ground battles, split into sub-units in rearguard actions, or moved back to cover successive key points.Farndale, pp. 43–4.Routledge, pp. 116–7. 4 AA Brigade's units were used by I Corps, with 4th AA Rgt engaging a series of attacks by 20–30 bombers escorted by fighters. The Gun-Laying (GL) radar sets were sent back, and I Corps employed the regiment's batteries on bridges and routes to cover its withdrawal against high level and dive-bombing attacks. The next six days saw alternate moves and deployments in small units of Troop and Section size at Armentières, Hazebrouck, Poperinghe and other places under shellfire and Stuka attack. When the supply chain failed, a search party found a stock of ammunition on a loaded train in a railway siding. 21/8th AA Battery fought hard until on 27 May it was surrounded by Panzers and engaged them at close range. The gunners were forced to remove their breechblocks and disable their guns under machine gun fire before assisting the infantry with their rifles while retreating to Dunkirk.
By 26 May the decision had been made to evacuate the BEF from Dunkirk (Operation Dynamo), with I Corps controlling the rearguard including 4 AA Bde. The Corps LAA regiment (52nd (East Lancashire) LAA Rgt) came under 4 AA Bde for the last part of the operation, and moved down to deploy on the Dunkirk beaches. The rest of the brigade was ordered to disable or destroy all equipment and prepare for evacuation.Ellis, Chapter XI.Ellis, Chapter XIV.Farndale, p. 63.Routledge, pp. 117–8. 4th AA Regiment assembled on the beach at Bray-Dunes on 29 May, where the men lay under air attack for 36 hours. On 31 May the regiment was allowed to organise its own evacuation by means of small boats and a 'pier' of abandoned trucks.
On arrival in England the AA troops were sent to various training camps to reform. Most were then deployed to reinforce Anti-Aircraft Command in defending the UK during the Battle of Britain and The Blitz.Farndale, Annex D.Routledge, Table LXV, pp. 396–7. Others, including Brigadier Slater and his 4 AA Bde HQ, were sent to reinforce Middle East Forces (MEF).Routledge, pp. 128–9.
Western Desert Campaign Order of Battle January 1941 On arrival in Egypt, 4 AA Bde assembled as a mobile formation in the rear areas under British Troops in Egypt (BTE). The Western Desert Force (WDF) had begun its campaign against the Italians in Libya (Operation Compass) and in the last weeks of January 1941 the Italians began a long retreat through Tobruk, Derna and Benghazi. By 31 January 1941, 4 AA Bde had moved up to join XIII Corps (formerly the WDF) at Mersa Matruh in the Western Desert with the following organisation:Farndale, p. 130.Joslen, p. 478.Routledge, Table XIX, p. 141. HQ 4 AA Bde 51st (London) HAA Rgt RHQ, 152, 153 HAA Btys 16 HAA Bty – attached from 2nd HAA Rgt 13th LAA Rgt RHQ, 37, 38 LAA Btys 155 LAA Bty – attached from 52nd (East Lancashire) LAA Rgt 1 Independent LAA Bty Detachment 5 Independent LAA Bty B squadron, Royal Wiltshire Yeomanry – organised as an AA/SL Bty
Siege of Tobruk Almost as soon as it arrived, 4 AA Bde had to send forward part of its strength to catch up with XIII Corps' advance. Two batteries of 51st HAA Rgt with 16/2 HAA Bty and 8th Australian LAA Bty went on to Derna and Benghazi, while 51st HAA Rgt's Royal Army Ordnance Corps (RAOC) workshop detachment remained at Tobruk and set about restoring some of the captured Italian AA guns to working order. 1 LAA Bty moved up as separate Troops attached to columns of 7th Armoured Division, covering of rough going in 30 hours. There was virtually no enemy air activity as the Italian Tenth Army collapsed, with many thousands surrendering, but within a few days aircraft of the Regia Aeronautica joined by the Luftwaffe began bombing the British forward supply point that had been established at Benghazi.Playfair Vol I, pp. 365, 374.
Meanwhile, MEF had to provide AA cover for the campaign in Greece: 2nd and 51st HAA and 13th and 52nd LAA Rgts had already sent individual batteries; now 16/2 HAA Bty was recalled from Benghazi to embark at Alexandria, a journey of , followed by 155/52 LAA Bty.Playfair Vol I, pp. 375–6.Routledge, pp. 144–5.
German intervention in the shape of General Erwin Rommel and his Afrika Korps quickly turned the tide in Libya. A swift breakthrough pushed British forces backwards. The two batteries of 51st HAA Rgt and 8 Australian LAA Bty at Benghazi were recalled, retiring first to Derna and then to Tobruk, in action most of the way. The German columns, heading for the Egyptian frontier, bypassed Tobruk, whose garrison prepared to defend the port. This was invested from 11 April, beginning the epic Siege of Tobruk lasting 240 days. 4 AA Brigade was a major element of the garrison, and had been reinforced just before the ring closed, with the arrival of 14th (West Lothian, Royal Scots) LAA Rgt (less one battery) and 235 (Kent) Battery of 89th (Cinque Ports) HAA Rgt (to replace the absent battery of 51st HAA Rgt). Eight static 3.7-inch guns had also been delivered by sea, making a total of 24 guns available, (although two were disabled early in the siege by premature bursts and the static guns had to be assembled and emplaced), and 152 and 235 Batteries each had an Italian 102mm gun in addition.Farndale, p. 162.Routledge, pp. 130–3, Table XX, p. 141.
Each mobile HAA troop established at least one alternative site and the guns were regularly switched between them, the empty sites being rigged up as dummies. The two available gun-laying (GL) radar sets had to be positioned away from the vulnerable gun sites and used for early warning to supplement the single RAF radar, and a close ring of searchlights operated round the harbour at night, able to illuminate enemy minelayers. Harbour defence was by pre-arranged barrages by five of the six HAA troops, the sixth troop remaining on watch for other raiders. Later a mobile troop was moved to one or other GL site to engage 'unseen' targets at night. Telephone lines were laid from the Gun Operations Room (GOR) near the harbour to Fortress HQ, all gun positions and all radars, and radio links were set up to any warships in the harbour or lying offshore.
Rommel made his first attack on the perimeter before dawn on 14 April but was driven out by a counter-attack. During this battle RHQ and 153 HAA Bty of 51st (London) HAA Rgt were attacked by Stukas; Lieutenant-Colonel Murray McIntyre was among those wounded, and RHQ was evacuated by sea to Alexandria that night. RHQ of 13th LAA Regiment took over command of the harbour area, while RHQ of 14th LAA Rgt commanded the perimeter area. Brigadier Slater acted as AA Defence Commander (AADC) for the whole Tobruk area, with RHQ 13th LAA Rgt providing the AADC for the harbour area.Farndale, p. 167.Farndale, p. 188.
The Official History records that the AA artillery in Tobruk was 'incessantly in action against attacks of all kinds, from all heights, but especially by dive-bombers'.Playfair, Vol II, p. 158. The LAA gunners needed quick reactions to deal with low-level fighter attacks and dive-bombers. The regimental historian notes that these Stuka attacks concentrated on gun positions, which was a serious threat to HAA sites, whose instruments could not cope with the rapid height changes. The gunners devised a tactic of opening fire with short Fuzes just before the dive started, to force the pilots to fly through a ring of bursts. The battery cooks, drivers and clerks then joined in, firing machine-guns and captured 20mm Breda guns. This aggressive method was known as 'Porcupine', and was so effective that the Luftwaffe changed to high-level bombing, where the GL radar could direct concentrations. The harbour could not be completely defended against air attack by day, but was always usable by night. Aircraft attempting to lay parachute mines in the approaches were usually driven off by a low-level concentration of all available guns into a searchlight-illuminated target area. The searchlights were only switched on once the GL radar had located the target.