page_title: 51st (London) Heavy Anti-Aircraft Regiment, Royal Artillery
section_title: Tobruk
hierarchical_section_title: 51st (London) Heavy Anti-Aircraft Regiment, Royal Artillery / World War II / Tobruk
caption_attribution_description: English: Tobruk 1941 - 1942: German bombs explode during one of the heaviest air raids on Tobruk. The photograph was taken from a trench adjoining an anti-aircraft gun
context_page_description: 51st (London) Heavy Anti-Aircraft Regiment was a volunteer air defence unit of Britain's Territorial Army from 1922 until 1955. During World War II it served in Norway, The Blitz, North Africa, and finally in Italy until the end of the war in Europe, by which time a proportion of the regiment's personnel were African soldiers, and the guns were engaging ground targets rather than aircraft.
context_section_description: On arrival at Tobruk, 51 HAA's workshop detachment set about restoring some of the captured Italian AA guns to working order, while the two batteries followed the WDF to Benghazi. But when German intervention turned the campaign in early 1941, the batteries were recalled, retiring through Derna to Tobruk, in action much of the way. By 7 April the whole regiment (less four guns still withdrawing from Gazala) was within the Tobruk perimeter. The German breakthrough bypassed the port, which was invested from 11 April, beginning the epic Siege of Tobruk lasting 240 days. 4th AA Brigade was a major element of the garrison, and had been reinforced just before the ring closed round Tobruk, with 235 (Kent) Battery of 89th (Cinque Ports) HAA Regiment arriving to replace 151 Bty. 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 152 and 235 Batteries each had an Italian 102mm gun in addition. On 14 April, Regimental HQ and 153 Bty were attacked by Stukas; Lt-Col McIntyre was among those wounded, and later that day RHQ was evacuated by sea to Alexandria. Thereafter, 152, 153 and 235 HAA Batteries, together with 51st HAA Regiment's workshops and signals, formed part of the Harbour Defended Area under the command of HQ 13th LAA Regiment.
  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 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. 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 Mk I) 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 ring of searchlights operated round the harbour at night. Harbour defence was by pre-arranged barrages by five of the six HAA troops, the sixth troop remaining on watch for other raiders. 152 Battery dug in west of the harbour engaged 1000 enemy aircraft in a six-month period. 4th AA Brigade recorded that there was a steady decline in numbers of aircraft attacking as the siege went on, with the attackers switching to high-level and night attacks. In the last two months of the siege, troops of HAA guns took it in turn to move out to the perimeter and take on ground targets under the control of 9th Australian Division. Their long-range harassing fire made up for the shortage of medium artillery. In September 1941, the batteries of 51st HAA Rgt were relieved and left Tobruk by sea to rejoin RHQ for rest and refit in Palestine.
caption: German bombs explode during one of the heaviest air raids on Tobruk. The photograph was taken from a trench adjoining an AA gun.
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