By the beginning of May 1941 the situation on the Egyptian border, the losses incurred in the recent attack and more crucially supply problems ruled out further German attempts to seize Tobruk in the immediate future. German and Italian forces in Libya required an estimated 30,000 tons of supplies per month purely to remain operational, with an additional 20,000 tons to build up stocks for future operations. However, there was only sufficient coastal shipping capacity to move 29,000 tons per month, the bulk of which had to be unloaded at Tripoli and then moved the remaining 1,000 miles or more to eastern Cyrenaica by road. Damaged docks, RAF bombing and Royal Navy activity meant Benghazi could handle only small coastal vessels on an intermittent basis, Buerat and Sirte were too small and Derna could only be accessed relatively safely by submarines carrying ammunition. Rommel’s activities had strained this tenuous logistic linkage to breaking point; as Generaloberst Halder, head of the Oberkommando des Heeres (OKH), noted in his diary: ‘By overstepping his orders Rommel has brought about a situation for which our present supply capabilities are insufficient.’ Rommel became aware of OKH’s displeasure with the Libyan situation on 3 May, after Generalleutnant Paulus had rendered his initial report. As well as reprimanding him for his reckless and wasteful conduct to date, OKH explicitly forbade Rommel from renewing the attack on Tobruk or anywhere else and specifically ordered him to hold in place. Rommel’s reaction to this can be well imagined, but the news came as a considerable relief to the Tobruk garrison; Morshead received an intercepted copy of the signal, hand carried by a destroyer captain, on 6 May. Rommel therefore had no option but to resort to the more traditional siege tactics of containing the Tobruk garrison while starving the fortress of supplies and reinforcements. Responsibility for carrying out the process thus passed to Fliegerführer Afrika, Generalmajor Stefan Fröhlich.
The Luftwaffe had been active over the Tobruk perimeter in support of ground forces from early April 1941 reconnoitring the perimeter defences and dropping leaflets urging the garrison to surrender, while dive-bombers from Sturtzkampfgeschwader (StG) 3 had engaged in harassing artillery positions and attacking the harbour. Mass raids on 14 and 17 April were followed by smaller, sustained attacks on 18 April on a variety of targets inside the perimeter including El Gubbi airfield. In all, between 11 and 30 April twenty-one separate dive-bombing attacks were recorded, involving a total of 386 aircraft. Luftwaffe activity followed a similar pattern in support of Rommel’s May Day attack, with eight separate attacks on British artillery positions in the vicinity of Fort Pilastrino between 28 April and 2 May. Attacks on targets in what was dubbed the forward area of the perimeter then fell away, apart from reprisal attacks in response to damage inflicted by the garrison’s artillery. This was due to the Luftwaffe shifting its attention to Tobruk harbour, although this was not a totally new departure. The harbour had been attacked on 12 and 13 April, sinking one merchantman and damaging another, and again on 18 and 19 April. It is unclear whether these attacks were part of a deliberate effort to alternate attacks between the perimeter and Tobruk proper or provoked by the presence of shipping in the harbour, but the latter was where the bulk of Tobruk’s anti-aircraft (AA) strength was concentrated; three aircraft were claimed shot down on 12 April and three more and two probables on 20 April, for example. The statistics gathered by the defenders illustrate the intensity of the struggle between the Luftwaffe and the AA gunners at this early stage of the siege. Between 10 and 30 April 1941 Tobruk’s AA guns claimed to have downed thirty-seven attackers, sixteen probables and to have damaged a further forty-three for the expenditure of 8,230 rounds of 3.7-inch and 25,881 rounds of 40mm and 20mm ammunition.
While the 4th AA Brigade and Luftwaffe were fighting their own war over Tobruk and the adjacent harbour, the Tobruk garrison was becoming accustomed to existence within the perimeter. A billet in Tobruk meant relatively comfortable and fairly civilised living conditions but with the ever present danger from the Axis air attacks that came in day and night. Troops on the perimeter, on the other hand, were rarely troubled by aircraft but had to be constantly on the alert for enemy patrols and the like while enduring extremely primitive and uncomfortable living conditions. The greatest trial was the fine, powdery dust that permeated food, weapons, vehicle engines and moving parts, clothing and living quarters to the extent that the men ended up eating and breathing it as a matter of course. This was especially troublesome for the troops stationed on the Blue Line and inward, due to the constant passage of vehicles, and matters were exacerbated overall by the dust storms that occurred every few days that reduced visibility to near zero and made movement difficult if not impossible. The dust was exacerbated on the perimeter and in units stationed in the open desert by large numbers of voracious fleas and clouds of flies. One NCO from an AA crew claimed the former were more of a tribulation than enemy bombs, and the latter were attracted to refuse, food, bare flesh and broken skin with manic tenacity, clogging eyes, ears and nostrils and making eating a one-handed trial. The arid conditions meant there were no mosquitoes and thus no malaria, and generally the health of the garrison remained good. The exception was the occasional outbreak of dysentery caused by failure to observe sanitary arrangements and drinking unchlorinated water, but this was largely eliminated with rigorous enforcement of the rules following an outbreak in June that laid low 226 men in a single week. The lapses with regard to water were understandable if not excusable, given that the daily water ration up to 19 June was four pints per man for all purposes; after that date it increased to six pints.
There was little wildlife in the perimeter apart from a species of small brown mouse and the odd jackal or gazelle, but the troops adopted a number of starving dogs and cats that had belonged to Tobruk’s evacuated civilian population. There was also a lone, aged sheep nicknamed ‘Larry the Lamb’ by the AA unit that adopted him as a mascot; the gunners had to post extra guards to prevent Larry augmenting the rations of some prowling Australian. The latter threat was not an idle one, and not merely because bully beef was the staple ration item for the first three months of the siege and beyond, occasionally replaced with canned bacon, herrings and M&V stew. The canned rations were augmented with bread from the ex-Italian bakery in Tobruk, margarine, sugar and jam, although the latter two were in short supply. The rations were barely adequate and nutritionally deficient even with the issue of concentrated vitamin C tablets in lieu of fresh fruit and vegetables, and the limited diet eventually began to take its toll, most markedly in the shape of ugly and painful desert sores. The ration situation improved from mid-July 1941, with fresh meat being served to troops in reserve positions once a month, fresh fruit and vegetables on a weekly basis and more regular issues of the latter in cans. Even so, when the 9th Australian Division’s infantrymen were examined after being relieved it was discovered that each man had lost up to twenty-eight pounds in weight.
The garrison routine settled into a pattern that would have been instantly recognisable to the First World War veterans in its ranks, with units being rotated regularly between the perimeter, the Blue line, reserve and manning the exposed positions facing the Ras El Medauar salient. Troops in the perimeter split their time between patrolling, and maintaining their positions, while units in the Blue Line were not only employed in digging defensive positions, but in laying mines, erecting and maintaining barbed wire entanglements and creating a third line of defence dubbed the Green Line. While in reserve the troops were allowed a few days’ rest by the sea, where they could launder their clothing, swim and simply soak up the sun in relative safety. It was not unusual for units in reserve to suffer more casualties from air raids than they incurred while manning the perimeter; on one occasion a platoon from the 2/43rd Battalion lost two killed and three wounded to bombs while engaged in road repairs, for example. There was thus no real escape from danger and the concomitant mental stress anywhere within the Tobruk perimeter, although significant efforts were made to maintain morale primarily via the provision of cigarettes, comforts and mail. A weekly issue of fifty cigarettes per man was made from the beginning of the siege, augmented with another fifty from unit canteens to those with the funds to pay for them from June. Additional cigarettes were distributed for free by the Australian Comfort Fund (ACF), an organisation set up during the First World War to support the troops by providing canteens, clubs, hostels and the comforts to stock them. The ACF also provided the Tobruk garrison with pre-stamped air-mail letter cards, writing paper, envelopes and stamps, with £3,200 of the latter being sold in one month alone. The mail was handled by an Australian postal unit located in what had been Tobruk’s bank which received an average of 700 bags of mail and despatched half that number per week through the siege, equivalent to 5,000 parcels and 50,000 letters; by August 1941 the unit was moving fifty tons of assorted mail per week.
The infantry were not employed solely in standing watch and maintaining their positions during their stints on the perimeter. Morshead implemented a policy of aggressive action and patrolling, partly to offset the enervating effects of boredom and partly to tie down as many Axis troops as possible to relieve the pressure on the Egyptian border. In essence Morshead’s policy amounted to a revival of the First World War practise of dominating no-man’s land, and this was literally the case on the southern and eastern sectors where the enemy positions were rarely more than a mile from the perimeter. Patrols up to twenty strong, carrying only weapons, ammunition and grenades leavened with Thompson guns and usually a single Bren for support were despatched almost every night, with socks over their leather-soled boots for stealth; special rubber-soled footwear and camouflage clothing became available in the later stages of the siege. If the target was an enemy position the patrol would navigate their way on compass bearings in the darkness, picking their way stealthily through the protective barbed wire, booby-traps and mines without alerting the sentries before attacking from the flank or rear. As well as inflicting casualties and unsettling the enemy a frequent objective for the patrols was to capture a prisoner for intelligence, often by penetrating beyond the enemy front line. On one occasion a patrol from the 2/23rd Battalion led by Captain Rattray captured a lone Italian sentry near the Bardia road after attracting his attention with a combination of low whistles and calling him comrade in his native tongue as they drew close enough to seize him. Among the most adept at this hazardous nocturnal activity were the dismounted armoured crewmen from the 18th Indian Cavalry Regiment, who gained a fearsome reputation among friend and foe alike. Many moved silently on rubber sandals fashioned from discarded vehicle tyres, and one group is reputed to have presented their commander with two sacks of severed enemy ears when the veracity of their post-patrol reports was questioned.
The most intense activity took place facing the Ras El Medauar. The creation of the salient added an additional five and a half miles to the perimeter that had to be built from scratch under the noses of Infanterie Regiment 115 holding the hill. The extra frontage obliged Morshead to press personnel from support units stationed in Tobruk into service as substitute infantry; the 2/1st Pioneer Battalion held a section of the line until mid-May, for example. Initially the new line was sketchy, with random patrolling by both sides between front lines to half a mile apart, but on 13 May the 18th Australian Brigade was ordered to take over the salient and push forward until in close contact with the German line. Conditions on the salient were the worst in the entire Tobruk perimeter, not least because the terrain was almost completely solid rock under a thin layer of fine sand. This meant that the troops were unable to dig in properly and had to make do with makeshift positions that were part sangar, part shell scrape, with no overhead cover. The latter deficiency was especially grievous because the presence of German observers on the Ras El Medauar made daylight movement impossible, and the troops holding the line were obliged to remain totally motionless throughout the hours of daylight, totally exposed to the sun and enemy artillery or mortars.
Allied activity on the front line in the salient thus became totally nocturnal, revolving largely around the arrival of rations from the rear. Breakfast was served at 21:30, hot meals at midnight and just before dawn, the latter being accompanied by hard rations for consumption during the coming day. Units could not bear such conditions for long, and men emerged from a week long tour on the salient undernourished, weak and frequently racked with dysentery. The traffic was not all one-way. On 12 May the 2/13th Battalion shot up a number of Germans who had taken up the habit of taunting the previous unit by walking around and shaking their bedding in the open, and A and B Companies from the same battalion sprang a successful hasty night ambush on German troops attempting to occupy some partly-completed positions in no man’s land fourteen days later. The Germans had to bring up five ambulances after first light to remove the resulting casualties, and the Australians made good use of the brief truce to openly examine their surroundings from a standing position in daylight.
The salient was also where Morshead’s strategy to keep the maximum number of Axis troops occupied on the perimeter was most successful, not least because Rommel had to keep hold of it as a springboard for future attacks into the Tobruk perimeter. The order for the 18th Australian Brigade to close up to the German front line on 13 May was part of a ploy to persuade Rommel that the garrison were about to attempt a break-out, in order to draw German troops away from an upcoming British attack on the Egyptian border. Throughout 14 May vehicles were driven back and forth near the south-western sector of the perimeter to simulate a pre-attack concentration, supported by spurious radio traffic. The following morning three Cruiser tanks and two platoons from the 2/12th Battalion attacked positions held by elements of the Pavia Division near defence Post S15, and in the afternoon the 2/10th Battalion launched another limited attack further north to straighten out its section of the line. The attacks succeeded in their intent. The Pavia Division infantry abandoned their positions, and RAF reconnaissance on 15 May noted German mechanised units moving toward Tobruk from Sollum to the east, and Axis armour concentrating west of Tobruk near Acroma.
In one way the deception succeeded rather too well, insofar as it provoked a strong German pre-emptive strike. After a two hour preparatory artillery and mortar bombardment the Germans attacked Posts S8, S9 and S10 in the late evening of 15 May supported by five Panzers, while the Italians counter-attacked S15. The attack was well organised, using coloured tracer ammunition to guide the troops toward their objectives, and went on throughout the night. One party penetrated into S9’s anti-tank ditch before being forced back by a counter-attack. The Germans did succeed in overrunning S10 with the aid of flame-throwers and close support from the Panzers, taking a number of the Australian defenders prisoner and cutting off S8 and S9. The Panzers withdrew before first light but German infantry held onto S10 and beat off a counter-attack by a platoon from the 2/12th Battalion just after dawn. Another attack at midday finally retook the post, capturing twenty-eight Germans and liberating three wounded Australians. Contact was re-established with S8 and S9 after dark on 16 May and in the nick of time; the posts had beaten off numerous attacks through the day, but by dusk were running dangerously short of ammunition.
Having gained the Germans’ attention, Morshead set about keeping it with a larger attack on 17 May that had the secondary intent of eroding the size of the German salient by taking S6 and S7, and S4 and S5 as secondary objectives. The attack was assigned to the 2/23rd Battalion, supported by nine Matildas, and began at 05:27 with an artillery bombardment from thirty-nine guns, thickened with indirect fire from twelve Vickers medium machine-guns from the 1st Royal Northumberland Fusiliers, a smoke barrage on the Ras El Medauar to blind German observation posts and a fortuitous early morning mist. Things did not go according to plan from the outset. The Matildas failed to reach the start line in time, lost touch with the infantry despite the efforts of the reserve platoons to attract their attention and abandoned attempts to find their way forward after becoming disoriented by a German counter-smokescreen. The Germans hit the attacking infantry with every weapon they could bring to bear, with AA guns firing shells fused to detonate overhead being especially troublesome. S7 was seized by Captain Ian Malloch’s Company in spite of this, but the troops could not be reinforced and by 07:30 the Germans had retaken it using Panzers. To the left Major W. H. Perry’s Company secured S6 and moved on to take S4, taking a total of twenty-three Germans prisoner, but were then cut off by the weight of German defensive fire. An attempt to reach them at 07:40 was driven off despite support from four Matilda tanks, although two Bren Carriers succeeded in delivering ammunition and rations to S6 under cover of the mist and dust.
With no further contact, 2/23rd Battalion HQ wrote off Perry and his men after Panzers were seen in the vicinity of the recaptured posts at around 09:00, until the Company Clerk, Corporal Fred Carleton, succeeded in reaching Battalion HQ three hours or more later. By this time Sergeant-Major W.G. Morrison and twenty-three men were holding out in sangars 200 yards from S6, and Morrison was able to break up several attacks during the course of the afternoon by calling down artillery fire via a field telephone line repaired by Private H.P Clark under heavy German fire; at one point Morrison was obliged to call down fire virtually on top of his own position. The little band was finally ordered to withdraw from their embattled outpost at dusk after a relieving attack was abandoned for want of tank support and Panzers were seen advancing on the sangars. Despite being ordered to abandon his five wounded after an attempt to lift them with two Bren Carriers was thwarted by a German anti-tank position, Morrison brought them and his fourteen able-bodied survivors out after a hair-raising crawl along an old Italian pipeline trench under constant German machine-gun fire; his was the only organised sub-unit to survive the day’s action. Only two of the ten officers from the two companies that spearheaded the attack escaped injury. Of the remainder, four were killed, one was seriously wounded and three were wounded and taken prisoner. In all the 2/23rd Battalion suffered twenty-five dead, fifty-nine wounded and eighty-nine missing, at least half of whom were believed killed. The Tobruk garrison thus paid a heavy price, and arguably one it could ill afford, for the privilege of diverting Axis attention from events on the Egyptian border, which did not meet expectations either.
The attack the Australian diversionary operation was intended to assist was Operation BREVITY, commanded by Brigadier Gott. Contemporary accounts cite the Operation as an attempt to relieve Tobruk, but Wavell’s typically wide-ranging and arguably contradictory instructions for the attack show this was not the case. Gott was ordered to recapture Sollum and Fort Capuzzo, inflict as much damage as possible on the enemy while not endangering his own force, and to exploit any success as far toward Tobruk as the logistic chain would permit. With large-scale reinforcements en route from the UK, Wavell allotted Gott all the armour and mechanised forces that could be mustered; two Squadrons of Cruiser Tanks from the 2nd RTR totalling twenty-nine vehicles, and two Squadrons of Matildas from the 4th RTR totalling twenty-four vehicles, along with the 22nd Guards Brigade mounted in vehicles borrowed from the 4th Indian Division, and the 7th Armoured Division Support Group. Artillery support was provided by the 8th Field Regiment RA, air cover by Hurricanes from No. 274 Squadron, and close air support by fourteen Blenheims from No. 14 Squadron. The attack began in the early hours of 15 May, and was initially successful. The Halfaya Pass, lost to Oberstleutnant Maximilian von Herff at the end of April, was retaken by the 2nd Scots Guards and a Squadron from the 4th RTR, the 1st Durham Light Infantry and more tanks captured Fort Capuzzo and the 7th Armoured Division Support Group made good progress toward Sidi Azeiz, ten miles north-west of Fort Capuzzo. Progress had not been easy or universal, however. The attackers were unable to clear enemy forces from the crucial approaches to the Halfaya Pass, and the various actions cost Gott’s force nine tanks destroyed or otherwise put out of action.
However, BREVITY had been compromised by poor signal security which allowed Rommel to send the Ariete Division to El Adem as a backstop, and more pertinently permitted the local German commander, Oberstleutnant von Herff, sufficient time to organise a response in advance. Thus after initially giving ground Herff launched a counter-attack with a battalion from Panzer Regiment 5 that recaptured Fort Capuzzo, from where he launched a second attack on 17 May after receiving reinforcements including another battalion of tanks from the newly arrived Panzer Regiment 8 from 15 Panzer Division. The reinforcement was not straightforward for Panzer Regiment 8 ran out of fuel after reaching Sidi Azeiz at 03:00 on 16 May and remained stranded for fourteen hours but Herff was able to begin his counter-attack in the early afternoon of 17 May, which forced the 7th Armoured Division Support Group back toward Bir El Khireigat, over ten miles south of Fort Capuzzo. Herff halted as ordered on a line running south and west from of Sollum, which efficiently screened and further British moves toward Tobruk. Overall BREVITY yielded only the recapture of the Halfaya Pass in return for six RAF aircraft lost, five Matildas destroyed and thirteen damaged. This was equivalent to the loss of three-quarters of the Matildas committed, while the 1st Durham Light Infantry suffered a total of 160 casualties in the fight for Fort Capuzzo. On the other side of the ledger German losses totalled three Panzers destroyed, twelve killed, sixty-one wounded and 185 missing, along with an unknown number of Italians taken prisoner. There matters rested, with a small British all-arms force built around the 3rd Battalion The Coldstream Guards holding the Halfaya Pass, for nine days while the Germans organised fuel supplies for their Panzers. Von Herff then retook the Pass with an attack that began on 26 May and forced the British back with the loss of five Matildas, twelve assorted guns and 173 casualties.
With the end of the fighting on the western sector of the perimeter the struggle for Tobruk shifted to the sky, most intensely over the harbour. Tobruk’s AA defences grew out of a relative handful of guns deployed to protect the harbour after Operation COMPASS, augmented with reinforcements brought in by sea. Between 6 and 12 April 1941 the 4th AA Brigade HQ and five fresh AA units arrived by ship, along with an additional twelve 40mm Bofors and eight 3.7-inch guns configured for static emplacement; all the latter were immediately co-opted for harbour defence despite a shortage of personnel to construct the necessary emplacements and man them. By 11 April the commander of the Brigade, Brigadier John Nuttall Slater, had at his disposal the 51st Heavy AA Regiment with two batteries of 3.7-inch guns, the 14th Light AA Regiment with a total of seventeen 40mm Bofors, the 306th Searchlight Battery and a number of signal and workshop units. These were supplemented with forty-two Breda 20mm automatic cannon, one twin 37mm Breda, four 102mm guns and two searchlights, all captured from the Italians; the static 3.7-inch guns were later formed into a third battery.
Within fifteen days of the 4th AA Brigade’s arrival, the 3.7-inch guns had been deployed around the harbour in six Sites labelled A, B, C, D, G and H, with B and D Sites being equipped with predictor apparatus for use against high-level targets and for night barrages. The newcomers soon found themselves directly targeted as the Luftwaffe attempted to suppress Tobruk’s AA defences. On 14 April 1941, for example, six to eight Junkers 87s attacked a 3.7-inch Site, killing two, wounding nine and destroying two battery vehicles. As a result of this 4th AA Brigade HQ ordered all gun positions and control posts to be dug in and reinforced, the preparation of alternate gun positions and purely dummy positions to confuse the high-level and dive-bombers; the former tended to make pre-planned attacks based on aerial photography, while the latter identified targets visually during their attacks. The dummy gun positions were sophisticated affairs carefully constructed to be indistinguishable from the real thing, complete with mocked-up guns, flash and dust simulators, vehicle tracks and dummy ammunition dumps. A defensive tactic nicknamed the ‘porcupine’ was also formulated, which involved attacked gun positions pointing all guns outward and firing at maximum rate at an elevation of sixty-five degrees or above. The wisdom and effectiveness of these precautions was to become apparent in due course.
Axis aircraft were an almost permanent feature in the skies above Tobruk during the siege, with high-level bombing raids a daily occurrence from the outset. Their frequency increased markedly from the end of May 1941, with ten to fifteen raids per day on some occasions, and fell off abruptly in October with only four in the first ten days of that month. In all, between 9 April and 10 October a total of 301 separate attacks were recorded reaching a peak with eighty-seven raids during July. The vast majority were directed against the harbour, Tobruk town and surrounding dumps and installations, although at least two high-level attacks were made against troops in the western side of the perimeter. Most were made from 18,000 to 25,000 feet, sometimes in formation and sometimes independently. Bombing from such altitude permitted most attacks to deliver their loads before the AA defences were aware of their presence, which was exacerbated by the location of most of the 3.7-inch gun Sites. While accuracy did not compare to that achievable by dive-bombing they did enjoy some success. The tail end of a stick of bombs destroyed a large dump of captured Italian ammunition four miles south-west of Tobruk town at the beginning of August, for example. For a while the bombers were able to confuse the AA fire control system by attacking in spaced increments; this was overcome by devolving fire control instructions from battery to gun section level, and the handicap of poor early warning was offset to some extent by authorising all guns to engage any target within range without waiting for permission.
There was no respite during the hours of darkness. The port was on the receiving end of a total of 908 night bombing raids between 9 April and 9 October, the peak month being August with 205. For the first two months raids averaged between one and three raids per night, and apart from a handful of aircraft dropping mines into the harbour, involved scattering Italian AR-4 anti-personnel devices across the town and harbour side. The devices were nicknamed ‘Thermos Bombs’ due to their resemblance to the vacuum flask of the same name and were dropped from low level, often in a tight pattern of thirty to forty at a time. The attackers launched a concerted attempt to block the harbour and approaches with mines on the nights of 21, 27 and 30 July, coming in at a variety of heights and directions to confuse the AA defences; this was the first time that the night attacks presented a serious threat to Tobruk. The raids refocused on the town and harbour installations in August, while the bulk of attacks in September took place on moonlit nights and were more balanced between mining missions and attacks on the town; the latter alternated between dropping Thermos devices and larger bombs, with some raids also dropping very large, parachute-delivered aerial mines. On 1 October the attackers dropped incendiary bombs on the town for the first time, but to little effect; as the official report dryly noted, by this point there was little left in the town to burn. The incendiaries nonetheless set parts of the town ablaze, but other enemy aircraft did not appear to make much use of the resulting illumination. Overall the night attacks did not present the AA defences with any special problems, apart from some minor modifications to fire control procedures. By the end of the siege the night barrage was employing twelve Bofors, seventeen 3.7-inch guns along with the five ex-Italian 102mm guns and twin 37mm Bredas.
However, the most intense struggle in the sky above Tobruk took place in daylight, between the AA defences and Sturtzkampfgeschwader 3’s dive-bombers. The contest began on 27 April with an attack on the AA positions covering the harbour by approximately fifty Junkers 87s, with twelve dive-bombers targeting each site. The gun positions went into porcupine mode, engaging all visible targets, and the tactic worked well for the A and C Sites; no bombs landed closer than fifty to a hundred yards and the newly dug gun pits effectively shielded guns, crews and ancillary equipment; only one man was killed and another wounded another. The B and D Sites were not so fortunate. The guns were not manned, the lookouts failed to spot the dive-bombers approaching from out of the sun, and the guns were not properly dug in, with flimsy parapets made of empty oil drums. The attack killed five, wounded over forty and put four of the 3.7-inch guns out of action for forty-eight hours; in addition the cables linking the individual guns to the predictor gear were shredded and the predicting equipment at both Sites was damaged. The B Site was hit again on 12 May, along with the G Site. According to the official report, the latter failed to defend itself with sufficient vigour while the B Site personnel panicked instead of manning their guns. Two men were wounded, one of whom died later, and four guns were put out of action for between twelve and twenty-four hours.
The process of measure and counter-measure set in these early encounters continued in the months that followed. The poor performances of 27 April and 12 May led 4th AA Brigade HQ to order all personnel in gun positions under attack to take part in the fight using small-arms, with only the unarmed being permitted to seek cover. Each gun pit was issued a Breda machine-gun for this purpose, although these had to be sited some distance away to avoid being unsighted by the dust kicked up by the larger guns. In addition, all gun pits and control posts were modified to withstand the impact of a 1,000 pound bomb landing within ten yards, and after members of a gun crew were injured by a primed 3.7-inch shell detonating after being struck by shrapnel, ammunition storage was modified so that stored shells faced outward. Observation showed that dive-bombing attacks were most accurate when delivered at a seventy to eighty degree angle, but this left them vulnerable to fire from light AA guns when pulling out at low level. Many attacks were thus made at shallower angles in the region of forty to fifty degrees, which allowed the dive-bombers to retain the safety of altitude at the cost of reduced bombing accuracy; bomb releases at altitudes as high as 6,000 to 8,000 feet were noted over Tobruk harbour, for example. It was also noted that accurate AA fire could provoke attackers to opt for the shallow angle attacks, and gun crews were encouraged to assist this tendency whenever possible.
By June 1941 the dive-bombers were becoming noticeably reluctant to press home their attacks. All of the Junkers 87s involved in attacks on AA positions on 1 and 2 June stayed above 3,000 feet, for example, with none of their bombs coming within 150 yards of their targets as a result; eyewitnesses also reported some aircraft jettisoning their bombs into the sea. The 2 June attack was accompanied by three Henschel 129 observation aircraft, presumably to gather information on the AA defences, and their presence was noted in subsequent raids too. The Luftwaffe tried a number of innovations during July. Some raids were preceded by small groups of Junkers 88s as a diversion, and on 4 July the dive-bombers avoided the 3.7-inch barrage by approaching from the west rather than south. Unfortunately this took them directly over a Bofors emplacement which promptly shot down five with a sixth being downed by a direct hit from a 3.7-inch shell. On 10 August Tobruk’s AA defences deployed a new weapon against an attack by eighteen dive-bombers, the Unrotating Projectile Rocket Barrage, consisting of salvos of 3-inch rockets containing contact-fused parachute mines on 400-foot cables. The mines were ejected automatically when the rocket reached an altitude of 1,000 feet, and the attacking aircraft were supposed to obligingly snag the cables and pull the mines onto themselves. Overall the system was not a success, although on this occasion its spectacular firing disrupted the incoming formation, two dive-bombers detonated mines with unknown results and another ended up with a mine parachute wrapped around its tail.
Over the next two weeks the attackers tried attacking through low cloud, approaching simultaneously from three different directions and preceding the latter with a diversionary gliding attack on the harbour. On the other side of the fence, the presence of the Henschel 126 prompted the AA defence to amend the porcupine defence by ordering only half the guns in any Site to fire at any one time; the reduction in the intensity of the barrage was considered worthwhile in order to avoid revealing the true gun strength of the defences. On 1 September the Luftwaffe roped in the Regia Aeronautica to assist in an attempt to overwhelm the AA defences by sheer weight of numbers. An estimated mixed force of 120 Junkers 87s, Fiat BR20s and Savoia Marchetti SM.79s attacked the harbour and surrounding AA positions, while additional aircraft bombed positions on the perimeter; this was the single heaviest air raid on Tobruk during the siege. The AA gunners claimed one Junkers 87 shot down, three probables and a number damaged in return for one killed, six wounded and up to five 3.7-inch guns put out of action by shrapnel, all of which were back in action by 16:30. In the event, this mass raid proved to be the penultimate major dive-bombing attack on Tobruk. The last, on 9 September, turned out to be something of an anti-climax, with only one Junkers 87 making a shallow angle attack on the harbour. The remainder of the formation were seen to jettison their bombs on finding no worthwhile shipping targets. Altogether Tobruk withstood sixty-two separate dive-bombings in the course of the siege, and over the same period the AA defences suffered a total of 158 casualties, forty of which were killed in action. In return they claimed ninety enemy aircraft shot down, seventy-four by light AA, a further seventy-seven probables and 183 damaged.