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: • 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. 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. 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. 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. 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'. 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.
Order of Battle, April 1941 The composition and dispositions of the brigade in the early part of the siege were as follows: • HQ 4 AA Bde
Harbour defended area: • RHQ 13th LAA Rgt • 152/51 HAA Bty • 153/51 HAA Bty • 235/89 HAA Bty • 40/14 LAA Bty • B Sqn, Royal Wiltshire Yeomanry, temporary S/L unit • 2 Trps 306 S/L Bty,
27th (London Electrical Engineers) S/L Rgt, arrived in April • GOR • 51 HAA Rgt Workshop, RAOC • 51 HAA Rgt Signal Section,
Royal Corps of Signals Perimeter defended area • RHQ 14th LAA Rgt • Trp, 38/13 LAA Bty • 39/13 LAA Bty • 57/14 AA Bty • 1 LAA Bty • 8 Australian LAA Bty • 13 LAA Rgt Workshop, RAOC • 13 LAA Rgt Signal Section, RCS
Total equipment: • 24 × 3.7-inch HAA Guns (16 mobile, 8 static) • 2 × 102 mm HAA guns (Italian) • 2 × 149 mm HAA guns (Italian) • 18 × Bofors 40 mm LAA guns (6 mobile, 12 static) • 42 × Breda 20 mm LAA guns (Italian) • 10 × S/Ls (8 90 cm, 2 Italian) • 2 × GL Mk I radar sets During September and October 1941 the whole of 9th Australian Division was relieved by sea and replaced by the British
70th Division and the
Polish Independent Carpathian Brigade. At the same time some of the AA units and personnel were also relieved: for example, 152 HAA Bty left for rest and refit in
Palestine, and RHQ and one battery of
69th (Royal Warwickshire Regiment) HAA Rgt arrived, while 5 Independent LAA Bty replaced 8 Australian LAA Bty. However, 153 and 235 HAA Btys, RHQ 14th LAA Rgt and 39, 40 and 57 LAA Btys saw the whole siege through. Also in September Slater went back to Egypt to take up the post of Brigadier, AA Middle East. He was awarded a
CBE in the
1942 New Year Honours and later that year commanded
7th AA Division at home in AA Command. Slater's work at Tobruk was later singled out for praise by the Australian
Official History. He was replaced as commander of 4 AA Bde by
Brevet Colonel John Muirhead, the CO of
74th (City of Glasgow) HAA Rgt, who had just been promoted to command
2 AA Bde but was transferred to Tobruk on 3 September. During the main part of the siege (10 April to 9 October), 40 AA gunners were killed and 128 wounded. There was then a lull in the fighting while both sides reorganised. The situation by 12 May 1942 was that 4 AA Bde was defending Tobruk with 68th (NM) HAA Rgt as its major subordinate unit, though some batteries were detached to
12 AA Bde defending fighter landing grounds for the
Desert Air Force and the army's railhead at
Fort Capuzzo. On 22 May the brigade was joined by 107 LAA Bty from
27th LAA Rgt, which formed the sole LAA defence of Tobruk harbour.
Fall of Tobruk During the
Battle of Gazala, beginning on 26 May, Rommel's Axis forces quickly broke into the British position and began attacking the defensive 'boxes'. After bitter fighting in the Gazala Line and the 'Cauldron', Eighth Army was forced to retreat. The British hoped to defend Tobruk as in the previous siege, but this time the Axis forces reached it before the defences were ready. The attack on Tobruk began on 20 June. After the preliminary air bombardment, Axis tanks made rapid progress through the perimeter defences. The 3.7-inch HAA guns had been deeply dug in for protection against dive-bombing, but a four-gun troop of 277 HAA Bty found themselves faced with action at short notice against
Panzer III and
Panzer IV tanks of
21st Panzer Division driving down the escarpment from 'King's Cross' towards the harbour. The gunners stripped down the walls of their emplacements to permit low-angle fire and engaged the tanks with armour-piercing and high explosive rounds. Together with some South African field guns and medium guns the position held up a Panzer battalion for four hours and knocked out four tanks, but the outcome was inevitable and the AA positions were 'overrun by swarms of enemy infantry'. Rommel himself referred to the 'extraordinary tenacity' of the strongpoint. Tobruk surrendered the following day, and around 33,000 Allied troops were captured, including 4 AA Bde. After the
fall of Tobruk, the Eighth Army retreated in confusion beyond the Egyptian frontier until the Axis advance was finally halted at
El Alamein.
Order of Battle 21 June 1942 The composition of 4 AA Bde when it was captured at Tobruk was as follows: • HQ 4 AA Bde • 68th (North Midland) HAA Rgt • RHQ • 277 HAA Bty • 282 HAA Bty –
attached from 88th HAA Rgt • 68 HAA Rgt Sigs • 68 HAA Rgt
Royal Army Service Corps (RASC) • 68 HAA Workshop Section RAOC • 5 LAA Bty • 107/27 LAA Bty • A & B Trps 43 LAA Bty,
61st LAA Rgt • 135
Z Bty • Dets 305/27 S/L Bty • 5 GOR • 4 AA Bde Sigs RCS • 4 AA Bde Company RASC • 4 AA Bde Workshops RAOC ==Reformed==