The 241-day 'Siege of Tobruk' began after the Axis forces advanced in the 'Western Desert Campaign' through Cyrenaica from El Agheila in 'Sonnenblume' against the Allied forces in Libya (10 April/27 November 1941).

Late in 1940, the Allies had defeated the Italian 10a Armata in the 'Compass' (i) operation (9 December 1940/9 February 1941) and trapped the remnants at Beda Fomm. During the early part of 1941, much of Lieutenant General Richard O’Connor’s XIII Corps (ex-Western Desert Force) was detached for redeployment to the the Greek and Syrian campaigns. As German troops and Italian reinforcements reached Libya, therefore, there remained only a skeleton Allied force that was short of men, equipment and supplies.

'Sonnenblume' (6 February/25 May 1941) forced the Allies into a retreat to the Egyptian border, but a garrison, comprising mostly Major General Leslie Moreshead’s Australian 9^th Division remained to garrison Tobruk and thereby deny the port to the Axis, while the XIII Corps reorganised and prepared a counter-offensive. The Axis siege of Tobruk began on 10 April, when the port was attacked by a force under Generalleutnant Erwin Rommel and continued during three relief attempts, namely 'Brevity' (15/16 May), 'Battleaxe' (15/17 June) and 'Crusader' (18 November/30 December). The continued Allied occupation of Tobruk deprived the Axis of the use of a supply port closer to the Egypt/Libya border than Benghazi, 560 miles (900 km) to the west of the Egyptian frontier, which was within the range of RAF bombers; Tripoli was 930 miles (1500 km) to the west in Tripolitania.

The siege diverted Axis troops from the frontier and the Tobruk garrison repulsed several Axis attacks. The port was frequently bombarded by artillery, dive-bombers and medium bombers, as the RAF flew defensive sorties from airfields far away in Egypt. Allied naval forces, such as the British Mediterranean Fleet (including the Inshore Squadron) ran the blockade, carrying reinforcements and supplies in and wounded and prisoners out. On 27 November, Tobruk was relieved by the 8^th Army, which controlled British and other Allied ground forces in the Western Desert from September 1941, in 'Crusader'.

The 'Western Desert Campaign' was fought from Mersa Matruh in Egypt to Gazala in Cyrenaica on the Libyan coast, an area about 240 miles (390 km) wide along Via Balbia on the coast, the only paved road. The Sand Sea 150 miles (240 km) inland marks the southern limit of the desert, which is at its widest at Giarabub and Siwa; in British parlance, the Western Desert came to include eastern Cyrenaica in Libya. Extending inland from the coast lies a raised, flat plain of stony desert, about 500 ft (150 m) above sea level, for 120 to 190 miles (200 to 300 km) to the Sand Sea. Scorpions, vipers and flies populated the region, which was inhabited by a small number of nomads. Bedouin tracks linked wells and the more easily traversed ground; navigation was by sun, star, compass and 'desert sense', the intuitive perception of the environment gained from experience. In the spring and summer, the days are miserably hot and the nights very cold; the sirocco (gibleh or ghibli), a hot desert wind, blows clouds of fine sand, which reduces visibility to a few yards and coats the eyes, lungs, machinery, food and equipment; motor vehicles and aircraft need special oil filters, and the barren ground means that supplies for military operations have to be transported from outside. German engines tended to overheat and tank engine life fell from 1,400 to 1,600 mi (2300 to 2600 km) to 300 to 900 miles (480 to 1450 km), which was made worse by the lack of standard parts for German and Italian types. The ground is a hard surface which drops to sea level in steps, and the coast is cut by south/north ravines.

The Italian fortifications at Tobruk included an outer perimeter, comprising a double semi-circle of dug-in strongpoints with concrete walls, positioned well for forward observation, an inner anti-tank ditch, some parts of which were behind barbed wire and/or included booby traps, as well as several more fortified positions closer to the port, at the junction of the road linking Bardia and El Adem and toward Fort Pilastrino.

In February 1941, the Allies defeated the 10a Armata of the Regia Exercita and 5a Squadra of the Regia Aeronautica, after which Allied leaders decided to hold the area with minimal forces and send the remainder of the XIII Corps to Greece. Morshead’s Australian 9^th Division and Major General Michael Gambier-Parry’s British 2^nd Armoured Division, less one brigade group sent to Greece, were left to garrison Cyrenaica under the control of Lieutenant General Sir Henry Maitland Wilson’s Cyrenaica Command, despite the inadequacy of its forces should the Germans send reinforcements to Libya. Command in Egypt was taken over by O’Connor and the headquarters of the XIII Corps was succeeded by the headquarters of Lieutenant General Sir Thomas Blamey’s Australian I Corps). It was believed by Wavell and the Middle East Command in Egypt that the Germans could not attack until May, when the Australian 9^th Division, two more divisions and support troops, particularly artillery, would be ready and the tanks of the 2^nd Armoured Division would have been overhauled.

The 2^nd Armoured Division had a reconnaissance regiment and Brigadier Reginald Rimington’s 3^rd Armoured Brigade, which had one understrength light tank regiment and another equipped with captured Fiat M13/40 medium tanks. The cruiser regiment arrived in late March with worn-out tracks, after many breakdowns en route and this brought the division up to the strength of an understrength armoured brigade. Most of the British tanks were worn out and the Italian tanks were slow and unreliable. The British 2^nd Support Group (similar to a small infantry brigade) had only one motorised infantry battalion, one 25-pdr gun/howitzer regiment, one anti-tank battery and one machine-gun company. The division was short of transport, and its workshops were undermanned and deficient in spare parts. Two brigades of the Australian 9^th Division were exchanged with two brigades of Major General John Lavarack’s Australian 7^th Division, which lacked sufficient training, equipment and transport.

Lack of transport made it impossible to supply any garrison to the west of El Agheila, the most favourable position for a defensive line, and also restricted the 2^nd Armoured Division to movement between supply dumps, still farther reducing its limited mobility. In February, Lieutenant General Philip Neame took over the Cyrenaica Command and predicted that the armoured division would lose many tanks through breakdowns should it ever be required to move far. Neame asked for an effective armoured division, two infantry divisions and adequate air support to hold the area, but was informed that there was little to send and none of that before April. Early in March, the Australian 9^th Division began to relieve Major General Iven Mackay’s Australian 6^th Division at Mersa Brega for shipment to Greece, which demonstrated the difficulty of tactical moves with insufficient transport, and it was withdrawn to the area to the east of Benghazi.

Neame was ordered to conserve the tank units, retire as far as Benghazi if pressed, abandon it if necessary, and hold the high ground nearby for as long as possible, with no prospect of reinforcement before May. Neame was to fight a delaying action along the Via Balbia toward Benghazi and then the defiles near Er Regima and Barce; the tanks would move to Antelat to operate against the attackers' right flank and rear moving up the road or across the desert to Tobruk, falling back on a flank if necessary. On 20 March, the 2^nd Armoured Division took over from the Australians, who moved back to Tocra, near Er Regima. The force was to use depots at Msus, Tecnis, Martuba, Mechili and Tmimi, El Magrun and Benghazi as a substitute for truckborne supply. Brigadier E. W. D. Vaughan’s Indian 3^rd Motor Brigade arrived late in March, with trucks but no tanks, artillery, anti-tank guns, and only half of its wireless sets; the brigade was based at Martuba, ready to use its vehicles to move toward Derna, Barce or Mechili.

On 24 March, Rommel advanced with the new Deutsches Afrika Korps. The 3^rd Armoured Brigade was to the south-east of Mersa Brega, where the 2^nd Support Group held an 8-mile (13-km) front; the Australians were 150 miles (240 km) to the north, less a brigade left at Tobruk, deficient in much equipment and out of contact with the 2^nd Armoured Division. Allied air reconnaissance had observed German troops to the west of El Agheila on 25 February, and by 5 March it was expected that the German commander would consolidate the defence of Tripolitania before trying to recapture Cyrenaica and then seek to invade Egypt, using bases at Sirte and Nofilia, but not before April. Rommel was identified on 8 March, but local intelligence was hard to find under the restrictions placed on forward formations and units to preserve the few troops and vehicles near the front and avoid the danger posed by the faster German eight-wheeled armoured cars, and this seriously inhibited Allied tactical reconnaissance.

On 3 April, Gambier-Parry had received a report that a large Axis armoured force was advancing on Msus, which was the divisional main supply dump. The 3^rd Armoured Brigade moved there and found that the petrol had been destroyed to prevent its capture. The tank brigade was reduced by losses and breakdowns to 12 cruiser tanks, 20 light tanks and 20 Italian tanks. Neame received conflicting reports about the positions of the Allied and Axis forces, and news on 5 April that a large Axis force was advancing on El Abiar led him to order the Australian 9^th Division back to Wadi Cuff and the elements of the 2^nd Armoured Division to guard the desert flank and retire to Mechili. Other reports led Neame to countermand these orders, which caused the Australians much confusion. On 6 April, Allied air reconnaissance reported that there were Axis columns in the desert and the Indian 3^rd Motor Brigade repulsed an attack at Mechili, which led to O’Connor at the headquarters of Cyrenaica Command (Neame had left to visit Gambier-Parry) to order a general withdrawal.

Rommel had intended to attack Mechili on 7 April but the Axis forces were scattered, short of fuel and tired. Generale di Brigata Fabris’s Raggruppamento 'Fabris moved forward during the morning, but the 132a Divisione corazzata 'Ariete' and Generalleutnant Johannes Streich’s Gruppe 'Streich took all day to arrive, having been attacked all day by the RAF. A Long Range Desert Group squadron had appeared from the south, to harass Axis movements. By the fall of night on 7 April, the Australian 9^th Division, less the 24^th Brigade, and British 2^nd Support Group had blocked the Via Balbia at Acroma, about 15 miles (24 km) to the west of Tobruk, where the Australian 18^th and 24^th Brigades were preparing the defences. (The 18^th Brigade had arrived from Egypt by sea after the despatch of the Australian 7^th Division to Greece had been cancelled.) A small force held El Adem, to the south of Tobruk, to observe the approaches from the south and south-west, and at Mechili Gambier-Parry had the headquarters of the 2^nd Armoured Division in soft-skinned vehicles and one cruiser tank, most of the Indian 3^rd Motor Brigade, M Battery of the 1^st Royal Horse Artillery, part of the Australian 2/3^rd Anti-tank Regiment and elements of other units.

The Germans made two efforts to bluff Gambier-Parry into surrender, but after he had received orders from Cyrenaica Command to break out and retreat to El Adem, he opted to attack at dawn and to gain a measure of surprise. On 8 April, A Squadron of the 18^th Cavalry broke through and then turned to attack Italian artillery, as some Indian troops of the 11^th Prince Albert Victor’s Own Cavalry (Frontier Force) got away. Most of the garrison was pinned down and after a second attempt at 08.00, when small parties of the 2^nd Royal Lancers escaped. The garrison had expended most of its small arms ammunition at the vision slits of the German tanks, which had hung back in fear of mines, so when the Italian infantry attacked the defenders had little ammunition available. Gambier-Parry and 2,700 to 3,000 British, Indian and Australian troops surrendered to Generale di Brigata Pietro Zaglio’s 17a Divisione fanteria 'Pavia'.

Supplies for the Axis force arrived by sea from Europe, and deliveries were then moved by road. After 'Compass' (i), only Tripoli remained to the Axis as a major port, and this possessed a maximum capacity of four troopships or five cargo ships, about 45,000 tons per month. The distance from Tripoli to Benghazi is 600 miles (970 km) along the Via Balbia, and this was only half-way to Alexandria. The road could flood, was vulnerable to the the attacks of British bombers, and the use of alternative desert tracks increased vehicle wear. The Axis advance of 300 miles (480 km) to the Egyptian frontier early in 1941 increased the road transport distance for supplies to 1,100 miles (1770 km). Benghazi was captured in April but coastal shipping could deliver only 15,000 tons and the port was within bombing range. Tobruk could handle about 1,500 tons per day, but lack of shipping made its capture irrelevant.

A German motorised division required 350 tons of supplies per day and moving the supplies 300 miles (480 km) took 1,170 two-ton lorries. With seven Axis divisions, air and naval units, the monthly requirement was thus 70,000 tons. Vichy France agreed to the use of Bizerte for supply delivers, but nothing passed through this port until a time late in 1942. From February to May 1941, a surplus of 45,000 tons was delivered. Attacks by Malta-based British forces had some effect but in May, the worst month for ship losses, but nonetheless some 91% of Axis supplies arrived. Lack of transport in Libya left German supplies in Tripoli and the Italians had a mere 7,000 trucks for deliveries to 225,000 men. A record amount of supplies arrived in June, but at the front the shortages worsened.

There were fewer Axis attacks on Malta from June and the quantity of Axis shipping sunk increased from 19% in July to 25% in September, when Benghazi was bombed and ships diverted to Tripoli; air supply in October made little difference. Deliveries averaged 72,000 tons per month between July and October, but the consumption of between 30 and 50% of fuel deliveries by road transport, combined with a truck unserviceability rate of 35%, reduced deliveries to the front. In November, a five-ship convoy was sunk during 'Crusader' and ground attacks on road convoys stopped journeys in daylight. The lack of deliveries and the 8^th Army’s offensive combined to force an Axis retreat to El Agheila from 4 December, crowding the Via Balbia on which Allied ambushes destroyed about half of the remaining Axis transport.

Work on the improvement of the fortifications at Tobruk had begun in March on the basis of the original Italian defences, two lines of concrete bunkers 8 to 9 miles (13 to 14 km) away from the port, making a perimeter about 30 miles (48 km) long, far enough out to keep the port out of artillery range. Few intermediate defences had been built by the Italians except at the Bardia/El Adem road junction, the barbed wire entanglements was in disrepair and an anti-tank ditch was unfinished. The Allies selected another line about 2 miles (3.2 km) back from the perimeter and worked on this while the original line was refurbished. Two battalions of the Australian 24^th Brigade and the newly arrived Australian 18^th Brigade, which had been detached from the Australian 7^th Division, assumed the defence of the perimeter and the Australian 20^th and 26^th Brigades took up a covering position on the outside until 9 April, while more work was done on the defences. Once inside, the three brigades of the Australian 9^th Division took over the defences and the Australian 18^th Brigade went into reserve.

A cadre of the British 3^rd Armoured Brigade was refitting at Tobruk, with personnel and equipment sent from Egypt by sea: this brigade had one regiment of armoured cars, two composite regiments with 15 light, 26 cruiser and a troop of four infantry tanks. There were four 25-pdr artillery regiments, two anti-tank regiments and one anti-tank company in each infantry brigade. The British 4^th Anti-Aircraft Brigade had 16 heavy and 59 light guns, all but two Bofors guns being sited around the harbour. Rear-area units had accumulated at Tobruk and one-third of the 36,000 personnel were in base units or local refugees and prisoners of war. Morshead planned an active defence and stressed that, with each battalions holding 5-mile (8-km) frontage, a break-in should be expected anywhere that the attackers made a serious effort and that any such break-in had to be eliminated as there would be no withdrawal.

By 8 April, the Germans' most advanced units had reached Derna, but some units which had cut across the chord of the Jebel Akhdar ran out of water and fuel at Tengeder. Generalmajor Heinrich von Prittwitz und Gaffron, commander of the 15^th Panzerdivision, was sent ahead with a column of reconnaissance, anti-tank, machine gun and artillery units to block the eastern exit from Tobruk as the 5^th leichte Division moved from the south-west and the 27a Divisione fanteria 'Brescia' advanced from the west. On 10 April, Rommel made the Suez Canal the objective of the Deutsches Afrika Korps and ordered that a break-out from Tobruk be prevented. On the following day, the port was invested, but the Axis rush ended with the 5^th leichte Division on the eastern side, the Gruppe 'Prittwitz' group to the south (Prittwitz had been killed and was succeeded by Generalmajor Hans-Karl Freiherr von Esebeck), and the 27^th Divisione fanteria 'Brescia' to the west. The 3^rd Panzeraufklärungsabteilung advanced as far as Bardia, and a composite force was sent to Sollum to try to reach Mersa Matruh. The Brigadier William Gott’s British Mobile Force, on the frontier from Halfaya Pass to Sidi Barrani, undertook a delaying action around Sollum and Capuzzo.

From 11/12 April, the 5^th Panzerregiment probed the defences of the Australian 20^th Brigade near the El Adem road, but the German tanks were held off by artillery fire. German infantry who reached the anti-tank ditch were forced back by Australian infantry. The Germans were surprised, having assumed that the shipping at Tobruk was to evacuate the garrison, and planned a night attack by the 5^th leichte Division for 13/14 April. Groups of Axis vehicles were attacked by the RAF’s Nos 45 and 55 Squadrons, which rearmed at the airfields inside the perimeter. The attack began after dark, with an attempt to get across the anti-tank ditch in the area to the west of the El Adem road in the sector pf the Australian 2/17^th Battalion, which the Australians repulsed. Another attempt was made later, and by dawn a small bridgehead had been established, where the 5^th Panzerregiment drove through and turned to the north, ready to divide into one column for the harbour and one to move west to stop the escape of the garrison.

The German tanks were engaged directly by the guns of the 1^st Royal Horse Artillery and veered away, only to drive into the path of the British cruiser tanks, waiting hull-down, and started to receive anti-tank fire from three sides: the German regiment lost 16 of 38 tanks and retreated. The Australian infantrymen had stood their ground and pinned down the German infantry. As the retreat continued, every gun and aircraft at Tobruk fired into the area, and the 8^th Maschinengewehrbataillon suffered the loss of about three-quarters of its men including its commander, Oberstleutnant Gustav Gustav Ponath, for the garrison’s loss of 26 men killed, 64 men wounded, and two tanks and a field gun knocked out. Attacks from the south were abandoned and the 5^th leichte Division dug in, with the Gruppe 'Schwerin' (renamed after Prittwitz’s death) to the east. In support, the Luftwaffe and Regia Aeronautica flew 959 sorties over Tobruk. On 14 April, 40 Junkers Ju 87 single-engined dive-bombers fell on the defences and on day 27 they succeeded in destroying a heavy anti-aircraft battery by swamping the defences with 50 aircraft allowing for an entire Staffel (squadon of 12 aircraft) to concentrate on each gun.

On 16 April, Rommel led an attack from the west, with the 132a Divisione corazzata 'Ariete' reinforced by the 62o Reggimento fanteria of the 102a Divisione motorizzato 'Trento'. The Australian 2/48^th Battalion counterattacked and took 803 prisoners. In the morning, the 132a Divisione corazzata attacked once again and some tanks reached the most advanced Australian posts, found that their infantry had not followed and retired after five tanks had been knocked out. Morshead ordered the garrison to exploit Axis disorganisation and their inability to quickly dig in on stony ground, through conducting patrols and small sorties. On 22 April, a company of the Australian 2/48^th Battalion, three infantry tanks and a troop of 25-pdr guns raided a hillock held by the Raggruppamento 'Fabris' to the south-west of Ras el Medauar; the raiders destroyed two guns and took 370 prisoners. At the same time a company of the Australian 2/23^rd Battalion advanced across the Derna road and in a costly attack took about 100 prisoners from the 27a Divisione fanteria 'Brescia', which led the Germans to hurry the 15^th Panzerdivision from Tripoli.

The defeat of the Axis attacks in April greatly improved the situation in Tobruk but General Hans Geisler’s X Fliegerkorps had sent 150 to 200 aircraft to Libya from Sicily during February, and these flew frequent dive-bomber sorties by day and medium bomber raids by day and night on the docks, buildings, anti-aircraft sites, artillery positions and the airfields. Westland Lysander single-engined army co-operation aircraft and all but the most essential ground crew of Nos 6 and 73 Squadrons were withdrawn to Egypt. At least 10 Hawker Hurricane single-engined fighters were based at the port during the day and on 19 April, Hurricane fighters of Nos 73 and 274 Squadrons intercepted a Ju 87 raid escorted by fighters. After another two days, No. 73 Squadron was down to five operational aircraft and all its pilots were exhausted. By 23 April, three more Hurricane fighters had been shot down and another two were damaged, and on 25 April the squadron was withdrawn. The fighters of No. 274 Squadron stayed at Gerawla and No. 6 Squadron remained at Tobruk to fly tactical reconnaissance sorties. Fighter cover could only be maintained at intervals by the last 14 Hurricane fighters available in the WesternDesert. Axis airfields at Gazala, Derna and Benina were bombed at dusk and night in an effort to limit Axis air attacks on Tobruk. Air Commodore Raymond Collishaw’s No. 204 flew long-range missions to attack German armour massing near Tobruk in the early stages of the siege: on 12 April, for example, Bristol Blenheim twin-engined light bombers of Nos 45 and 55 Squadron, operating from airfields in Egypt, attacked German tank formations near the port. The attack succeeded in breaking up the German advance.

Collishaw wrote to Air Marshal Arthur Tedder, the deputy commander of the RAF Middle East Command, on 24 April that in his view the situation in the air had rapidly deteriorated. The arrival of two German fighter wings (Jagdgeschwader 27 and Zerstörergeschwader 26) near Tobruk allowed the enemy German air formations to arrive at great height within just 10 minutes of the sounding of an air raid warning, leaving British fighters at lower altitude and a great disadvantage. Collishaw added that attrition had caused 'a serious reduction in our fighter force'. The bombardment and close air support operations in the initial phases were carried out by Lehrgeschwader 1, III/Sturzkampfgeschwader 1 and II/Sturzkampfgeschwader 2. Collishaw noted the aggression shown by Axis aviation and reported to Tedder that No. 274 Squadron, which had only 13 fighters available on 23 April, formed the major part of the fighter defence for Egypt and that he was therefore 'loathe to send them to Tobruk'. As Collishaw wrote his letter, the RAF lost a further six aircraft over Tobruk, equating to very heavy losses given the small contingent defending the port. Collishaw requested Tedder’s advice. Air Chief Marshal Sir Arthur Longmore, commander-in-chief of RAF Middle East Command. cabled the Air Ministry in London to the effect that he wished to operate in greater strength, and complained that reinforcements and fresh pilots were needed to replace the exhausted No. 73 Squadron. He told London that to maintain patrols, the fighters were forced to refuel at Sidi Barrani, thereby granting Axis air units a free hand over Tobruk but arguing that without patrols to defend fighter squadrons refuelling at Tobruk on the ground, they were 'hostage to a fortune we cannot afford'. On 1 May, for example, No. 274 Squadron lost all six Hurricanes it sent on a single mission when a flight of Messerschmitt Bf 109 single-engined fighters of JG 27 engaged them from a superior altitude over Tobruk.

Between 1 and 14 May, each side paused to stockpile supplies for the next stage of the battle. Of stated losses between 10 April and 14 May (excluding claims made by either side), No. 73 Squadron lost 15 fighters and five damaged. Five pilots were killed, one captured and one wounded. No. 274 Squadron lost six fighters, three pilots killed and two captured. No. 45 Squadron suffered the loss of three aircraft and five pilots killed, while Nos 55 and 6 Squadrons lost one and two respectively. No. 39 Squadron lost three bombers and No. 14 Squadron one for a total of 31 aircraft. Reported German losses, excluding RAF claims, were lower. III/StG 1 and II/StG 2 lost eight aircraft between them, while III/ZG 26 reported three aircraft destroyed and one damaged, two men killed, one wounded and three captured. III/LG 1 reported the loss of one aeroplane. JG 27 suffered the loss of four fighters, three damaged and three pilots killed. The Regia Aeronautica’s 151o Gruppo reported two aircraft destroyed and one damaged.

The intensity of the battle for air superiority was mirrored by the air war over the sea as the Luftwaffe and Regia Aeronautica attempted to cut off sea traffic supplying the defenders. The air/sea battle, after the failure of 'Battleaxe', was the main sector of operations for Allied and Axis aviation throughout the summer. StG 3, another Stuka dive-bomber wing, arrived in Africa during the summer. The eight-month long siege was costly for the Stuka Gruppen. At the end of April, virtually all Tobruk-based fighters had been removed from the encircled port, and the Ju 87 dive-bombers were facing defenders with anti-aircraft artillery numbering 88 guns including 28 heavy pieces with a calibre of 90 mm (3.54 in) of greater. Ships lent their weapons to the defenders: for example, the gunboat Ladybird, which was sunk in shallow waters to deck level by II/StG 2, was still able to use her 3-in (76.2-mm) deck guns. In April, Draco, Bankura, Urania and the armed boarding vessel Chakla were sunk by Axis aircraft, and on 4 May the hospital ship Kapara was damaged, evoking Allied fury.

The arrival of Italian-flown Ju 87 dive-bombers of the 97o Gruppo resulted in the sinking of the 3,741-ton tanker Helka on 25 May before she could reach Tobruk. The unit involved, the 239a Squadriglia, became one of the most successful over Tobruk. The escorting sloop, Grimsby, was damaged, and sunk by 3./StG 1. Commensurate with the sinking of Fiona and Chakla in April, the burden fell to the destroyers of Admiral Sir Andrew Cunningham’s Mediterranean Fleet to carry the burden, but supply operations in daylight and on moonlit nights proved hazardous. On 24 June the sloop Auckland was sunk by the 239a Squadriglia, which also sank the destroyer Waterhen. The vessel had just survived an attack by Junkers Ju 88 twin-engined bombers of III/LG 1 and the dive-bombers of II/StG 2. The lack of fighters made for an uncomplicated engagement between the ship’s gunners and German pilots. The gunners changed their tactics from a sustained barrage at a fixed altitude, to a staggered and thickened belt, at various altitudes covering some 3,300 ft (1000 m) or more, thereby forcing the dive-bombers to fly through fire for much longer periods. The gunners spread their fire from laterally to prevent German pilots from travelling down the side of the barrage and sliding in underneath it. The dive-bombers were active in night operations. On 26/27 October 1941, I/StG 1 attacked a convoy transporting 7,000 British and Polish soldiers with munitions on passage to Tobruk. A dive-bomber attack sank the cruiser minelayer Latona with a direct hit even though the ship could reach 40 kt. The destroyer Hero was badly damaged in the same attack.

In March, destroyers were withdrawn from the Inshore Squadron to escort 'Lustre' convoys to Greece, and in April four more ships joined the squadron. As the army retreated to Tobruk and the Libyan/Egyptian frontier, coastal operations were conducted on the nights of 10 and 11 April by gunboats, which bombarded Axis transport on the Via Balbia around Bomba and Gambut airfield, and on the night of 12 April six destroyers and two cruisers made a coastal sweep from Ras Tayones to Ras et Tin. On he following day, three ships bombarded Sollum, and on 15 April transport was bombarded at Bardia and Capuzzo, as Gazala airfield was shelled again. For the rest of April, naval bombardments continued along the Libyan coast on the Via Balbia, airfields and ports. A commando raid was carried out on Bardia and supply runs began to Tobruk. From 11 April to 10 December, 47,280 men were taken from Tobruk, 34,113 were brought in and 33,946 tons of supplies were delivered; 34 ships were sunk and 33 damaged.

The raid on Bardia was planned for the night of 19/20 April, by A Battalion of Colonel Robert Lay’s 'Layforce' to disrupt Axis lines of communication and damage installations and equipment. The landing force reached the target area in the infantry landing ship Glengyle, which was escorted by the light anti-aircraft cruiser Coventry and the Australian destroyers Stuart, Voyager and Waterhen. The commandos of and one troop of tanks from the Royal Tank Regiment were to land on four beaches from LCA assault landing craft. On arrival, one LCA could not be lowered and there were difficulties releasing the others. On the run-in, there were no lights to guide the craft in to the beach, because the advance canoes of the Folbot (folding boat) section had been delayed, when their carrier, the submarine Triumph, had to dive and take evasive action when it was mistakenly attacked by Allied aircraft. As a result of these issues the main force was late and landed on the wrong beaches, albeit unopposed. Once ashore the commandos found that the port was empty of Axis forces, and faulty intelligence meant that some objectives were missed while others were found not to exist. The commandos destroyed an Italian supply dump and a coastal artillery battery before re-embarking. Some 70 commandos became lost, ended on the wrong evacuation beach and were taken prisoner.

After the failure of their attempt to capture Tobruk off the march, the Comando Supremo and the Oberkommando der Wehmacht agreed that Tobruk should be captured and supplies accumulated before the Axis advance into Egypt was resumed. Rommel thought that Tobruk could be taken only by a deliberate attack, which could not begin until support units had arrived in the area and the Luftwaffe had been reinforced, particularly with transport aircraft to carry ammunition, fuel and water. On 27 April, Generalmajor Friedrich Paulus, a deputy chief of the general staff, arrived from the Oberkommando des Heeres in Berlin to question Rommel on his intentions, impress on him that there was little more help available and to forecast the defensive possibilities of the area should Sollum be lost. Paulus refused to allow an attack planned for 30 April until he had studied the situation, and on 29 April he allowed the attack to go ahead, as did Generale d’Armata Italo Gariboldi, the Italian commander-in-chief in North Africa, who had arrived on 28 April. Nothing more ambitious than securing the Axis hold on the Egyptian frontier, from Siwa Oasis north to Sollum, was envisaged.

The Tobruk garrison continued work on the defences and sowed minefields, the first being planted in the south-west, between the outer and inner perimeters. Some 12 infantry tanks had been delivered among the 5,000 tons of supplies landed during the month, despite Axis bombing of the harbour and the sinking of two supply ships. The Axis attack was to be made in the south-west, either side of the hillock of Ras el Medauar, about two weeks after the previous attempt, using the 5^th leichte Division on the right and the 15^th Panzerdivision on the left, even though this latter had only recently arrived in Africa. At 08.00 on 30 April, the divisions were to break into the Tobruk defences, followed by assault groups from the 132a Divisione corazzata and the 27a Divisione fanteria to roll up the flanks. German infantry were to press forward to reconnoitre the vicinity of Fort Pilastrino and establish whether or not the attack could continue to the harbour. If not, the Italian infantry would dig in on the flanks and artillery would be moved forward for an attack the next day.

The attack came in the area held by the Australian 26^th Brigade, which had the 2/23^rd and 2/24^th Battalions in the line and the 2/48^th Battalion in reserve at Wadi Giaida. The Australians expected an attack, after withstanding bombing and artillery fire on the perimeter defences on 29 April, and Axis forces seen massing in the evening of 30 April had been dispersed by artillery fire. The Australian posts on each side of Ras el Medauar were shelled and bombed, and German troops began to dribble forward under cover of dust and the gathering darkness. By 21.30 the Germans had created a small bridgehead as planned, but several Australian posts held out, the reconnaissance party vanished and the Italian troops were not able to reach their objectives. The night passed in confused fighting as the Germans tried to reorganise and mop up at Ras el Medauar and attack to the south-west along the perimeter. The new attack failed, and by morning some of the Australian posts were still holding out.

A thick mist rose and the German armour moved to the east rather than south-east as planned, and then ran into the new minefield, where they were engaged by anti-tank guns and repulsed. Tanks of the 15^th Panzerdivision attempted to drive to the north but were prevented from doing so by anti-tank fire. No German reserves were left and the most advanced troops were to the south of Wadi Giaida, tired and isolated in a sandstorm. Paulus judged that the attack had failed and Rommel decided to attack on the right to widen the breach. In the afternoon, German tanks attacked to the south-east in the direction of Bir el Medauar, and Morshead sent 15 cruiser and five infantry tanks to counterattack. The German attack was stopped for a loss of five British tanks, and in the evening the Australian 2/48^th Battalion counterattacked Ras el Medauar but met determined resistance and was repulsed. During the day, Nos 73 and 274 Squadrons had maintained standing patrols over the area and on the morning of 2 May, the fighting around Wadi Giaida continued in a dust storm, as German troops tried to trickle forward. On the night of 3 May, the Australian 18^th Brigade made a converging counterattack with two battalions, which lost co-ordination, failed and was brought to an end to avoid it being caught in the open at the arrival of dawn.

The Axis attack had overrun the perimeter defences on a 3-mile (4.8-km) front to a maximum depth of 2 miles (3.2 km) and captured higher ground useful as a jumping-off position and on which observation points could be established, for a loss of 650 German and 500 Italian casualties. The 8o Reggimento Bersaglieri of the 132a Divisione corazzata had captured most of the Australian positions. Paulus ordered that no more attacks were to be made unless the Allies were evacuating the port. The Deutschs Afrika Korps was to hold Cyrenaica regardless of who held Sollum, Bardia or Tobruk, and a new line was to be built farther back to the west at Gazala. In a report on 12 May, Paulus wrote that sea communications between Italy and Libya should be reinforced, that any air and anti-aircraft units sent to Libya should be German and that the army in Libya needed ammunition, fuel and food first, then more vehicles before the despatch of more men, among whom medium artillery and anti-tank gun crews should have priority.

The Tobruk garrison now settled into a routine of patrols, air raids and minor attacks, some to regain positions in the Medauar salient and some in connexion with operations by Lieutenant General Sir Noel Beresford-Peirse’s Western Desert Force, which had been reactivated as successor to O’Connor’s XIII Corps.

The Twin Pimples was a defensive strong point outside Tobruk, on two closely spaced hills overlooking the Tobruk perimeter. It was held by Italian troops, and the 18^th King Edward’s Own Cavalry (normally part of the Indian 3^rd Motor Brigade) held the perimeter opposite. No. 8 Commando was selected to carry out an attack on the Twin Pimples, and with the Indians undertook patrols for several days to reconnoitre the ground. The 18^th Cavalry Regiment was to mount a diversion, while 43 members of No. 8 Commando and some Australian engineers crossed the Italian forward positions and a supply road, to attack the Twin Pimples from the rear. The commandos advanced at 23.00 on the night of 17/18 July and crossed the Italian lines undetected. At the supply road they took cover, waited until 01.00 and then edged forward just before the diversion by the 18^th Cavalry. The diversion attracted Italian machine gun fire and flares lights as the commandos got within 30 yards (27 m) of the Twin Pimples before challenge, at which the commandos attacked. The password 'Jock' was used when a position had been taken and the Italians were swiftly overcome. The Australian engineers planted explosives on several mortars and an ammunition dump. The plan assumed that it would take 15 minutes for Italian artillery to open fire on the captured trenches, and the raiders were only about 100 yards (91 m) away when shells began to rain down on the position they had just left.

'Brevity' (15/16 May) was a limited offensive to inflict attrition on the Axis forces and to secure positions for a general offensive toward Tobruk. The Allies attacked with a small armour and infantry force in three columns and seized the top of the Halfaya Pass, Bir Wair and Musaid, then pressed forward to take Fort Capuzzo. The coastal group failed to capture the bottom of the Halfaya Pass. The garrison on the eastern side of Tobruk’s defences was strengthened in case of a sortie and a German counterattack recovered Musaid. The coast group eventually overran the foot of the pass. On the next day, however, Allied retirements, in the face of German counterattacks, to a line from Sidi Omar to Sidi Suleiman and Sollum, left all but the Halfaya Pass in German hands. On 26 May, the German 'Skorpion' attack on the pass succeeded and the Allies were ejected. 'Brevity' thus failed to achieve most of its objectives, holding the Halfaya Pass only briefly. The Allies suffered 206 casualties, as well as five tanks destroyed and another 13 damaged. German casualties were 258 men, as well as three tanks destroyed and several damaged. The Italians had 395 casualties including 347 men taken prisoner. On 12 May, the 'Tiger' convoy lost one ship but reached Alexandria with 238 tanks to re-equip the 7^th Armoured Division, as well as 43 aircraft. On 28 May, planning began for 'Battleaxe'.

'Battleaxe' (15/17 June 1941) was designed to lift the siege of Tobruk and to capture eastern Cyrenaica. The attack was to be conducted by the 7^th Armoured Division and a composite infantry force based on the Indian 4^th Division headquarters with two brigades. The infantry were to attack in the area of Bardia, Sollum, Halfaya and Capuzzo, with the tanks guarding the southern flank. The Tobruk garrison was to stand by but not to sortie until the XIII Corps drew close. The Halfaya Pass attack failed, Point 206 was captured and only one of three attacks on Hafid Ridge succeeded. At the end of 15 June only 48 British tanks remained operational, an on the following day a German counterattack forced back the Allies on the western flank but was repulsed in the centre; the Allies were reduced to 21 cruiser tanks and 17 infantry tanks. On 17 June, the Allies evaded encirclement by two Panzer regiments and ended the operation. The Allies had sustained 969 casualties, 27 cruiser and 64 Infantry tanks were knocked out or broke down and were lost; the RAF lost 36 aircraft. The German losses were 678 men, and the Italian losses are not known, and the Germans lost 12 tanks and 10 aircraft. In the aftermath of this failure, Wavell, Beresford-Peirse and Creagh were all sacked, and General Sir Claude Auchinleck took over as commander-in-chief in the Middle East.

In the middle of 1941, as commander of the Australian Imperial Force and with the support of the Australian government, Blamey requested the withdrawal of the Australian 9^th Division from Tobruk. Blamey wrote that the health of the Australian division had deteriorated 'to the point where it was not longer capable of resisting attack'; he also wanted to unite Australian forces in the Middle East. Auchinleck agreed, but noted that a troop movement of this magnitude could be made only through the employment of fast warships during moonless periods, to evade air attacks. At this time the Mediterranean Fleet was busy elsewhere, the Inshore Squadron was carrying supplies into Tobruk, and 'Crusader' was being prepared, but the Australian withdrawal began in the moonless period of August, and from between 19 and August, 6,116 men of the Free Polish Carpathian Independent Rifle Brigade and Free Czechoslovak 11^th Infantry Battalion, and 1,297 tons of stores were landed. The Royal Navy took out 5,040 men of the Australian 18^th Brigade and the Indian 18^th King Edward’s Own Cavalry, on three destroyers, a minelayer and one destroyer carrying supplies, with cruiser escorts as anti-aircraft ships, a cruiser and a destroyer being damaged. Between 19 and 27 September, the British 16^th Brigade, Major General Ronald Scobie’s British 70^th Division, the headquarters of the British 32^nd Army Tank Brigade and the 4^th Royal Tank Regiment with 6,308 men and more than 2,000 tons of supplies arrived, while 5,989 men of the Australian 24^th Brigade left, with no loss of ships. Between 12 and 25 October, the rest of the 70^th Division was delivered and most of the Australians removed. Ship losses on normal delivery runs led to the Australian 2/13^th Battalion and two companies of the 2/15^th Battalion remaining in Tobruk. Command of the garrison passed from Morshead to Scobie.

'Crusader' began on 18 November with an outflanking movement that brought the 8^th Army to within 30 miles (48 km) of the Tobruk perimeter. It was planned that the 70^th Division would break out from Tobruk on 21 December, to cut the German line of communication to the troops on the border to the south-east. The 7^th Armoured Division would advance from Sidi Rezegh, to rendezvous and roll up the Axis positions around Tobruk. The 2^nd New Zealand Division, attached to XIII Corps, would take advantage of the distraction of the 21^st Panzerdivision and 15^th Panzerdivision to advance to the Sidi Azeiz area overlooking the Axis defences at Bardia. The attack of the 70^th Division surprised Rommel, who had underestimated the size of the garrison and number of tanks in Tobruk. A three-pronged attack by the 2/King’s Own on the right flank, the 2/Black Watch in the centre and the 2/Queen’s Own on the left flank advanced to capture a series of strong points leading to Ed Duda. By the middle of the afternoon, the Allies had advanced about 3.5 miles (5.6 km) toward Ed Duda on the main supply road, where they paused as it became clear that 7^th Armoured Division would not arrive. The central attack by the Black Watch involved a charge under massed machine gun fire to strongpoint Tiger, and resulted in 201 casualties. On 22 November, Scobie ordered the position to be consolidated and the corridor widened, ready for the 8^th Army’s arrival. The 2/York and Lancaster Regiment, with tank support, took strongpoint Lion leaving a 7,000-yard (6400-m) gap between the corridor and Ed Duda. On 26 November, Scobie ordered an attack on the Ed Duda ridge and in the early hours of 27 November, the Tobruk garrison captured the ridge and later met a small force of New Zealanders advancing from the south. The 7^th Armoured Division had planned its attack northward to Tobruk for 08.30 on 21 November. At 07.45 patrols reported the arrival from the south-east of about 200 tanks. The 7^th Armoured Brigade and a battery of field artillery turned to meet this threat and without the tanks, and the northward attack by the Support Group failed; by the end of the day, the 7^th Armoured Brigade had only 40 of 160 tanks still left in operational condition.

On 22 November, the 25a Divisione fanteria 'Bologna' repulsed an attack from Tobruk toward Sidi Rezegh, and on the next day Rommel sent the Deutsches Afrika Korps toward the Egyptian border, in what became known as the 'Dash to the Wire', to exploit the victory and destroy the XXX Corps. The blow fell mostly on empty desert and gave the 8^th Army time to regroup and rearm. The Deutsches Afrika Korps was ordered back to Tobruk, where the 70^th Division and the New Zealand Division had gained the initiative. At 12.00 on 27 November, the 15^th Panzerdivision reached Bir el Chleta and encountered the British 22^nd Armoured Brigade, now reduced to a composite regiment of fewer than 50 tanks, which was joined later by the British 4^th Armoured Brigade. As night fell the British tanks disengaged and the New Zealand Division, fighting at the south-eastern end of the corridor into Tobruk, was threatened by the Deutsches Afrika Korps. On 4 December, Rommel attacked Ed Duda and was repulsed by the 14^th Brigade of the 70^th Division. Rommel ordered a retirement from the eastern perimeter of Tobruk in order to concentrate against the XXX Corps to the south. On 7 December, the 4^th Armoured Brigade engaged 15^th Panzerdivision and knocked out 11 German tanks. Rommel was told on 5 December by the Comando Supremo that supply could not improve until the end of the month, when airborne deliveries from Sicily began. Rommel therefore decided to abandon the 'Siege of Tobruk' and withdraw to Gazala, and this led to the relief of Tobruk and the occupation of Cyrenaica.

For much of the siege, Tobruk had been defended by the Australian 9^th Division and other troops. Wavell had ordered Morshead to defend the port for eight weeks, and the Australians in fact held Tobruk for more than five months, before being gradually withdrawn during September and replaced by the British 70^th Division, the Free Polish Carpathian Brigade and the Free Czechoslovak 11^th Infantry Battalion (East). The fresh defenders held Tobruk until they broke out on 21 November and held open an 8-mile (13-km) corridor, unsupported for several days, then captured Ed Duda on 27 November to link with the advancing 8^th Army during 'Crusader'.

The 'Tobruk Ferry Service', made up of Royal Navy and Royal Australian Navy warships, played an important role in the defence of Tobruk through the provision of gunfire support, the delivery of supplies and fresh troops and the evacuation of the wounded. Control of Tobruk was useful to the Allies because it was the only significant port to the east of Benghazi and west of Alexandria. The supply of Axis troops on the Egyptian frontier could have been eased by sea transport to Tobruk. The siege of Tobruk was the first occasion in the war that German armoured formations had been stopped. The 'Siege of Tobruk' was lifted in December 1941 in the course of 'Crusader', but Axis forces recaptured the port on 21 June 1942 after defeating the 8^th Army in the 'Battle of Gazala'.] During the course of the siege, two destroyers, three sloops, seven anti-submarine vessels and minesweepers, seven store carriers and schooners, six A lighters and one fast minelayer had been sunk, a total of 26 ships. Seven destroyers, one sloop, 11 anti-submarine and minesweeping vessels, three gunboats and one schooner had been damaged, a total of 23 vessels. Six merchant navy ships and one schooner had been sunk and six merchant ships damaged. Thus a total of 62 vessels had been sunk or damaged.

The 'Rats of Tobruk' suffered at least 3,836 casualties, there being a small difference in Australian casualty figures quoted in the Australian and British official histories. Most of the Australian garrison was withdrawn from Tobruk between August and October, but others remained in Tobruk for the duration. The Australian official history records the casualties of the Australian 9^th Division between 8 April and 25 October, including two days before the siege started, as 746 men killed, 1,996 wounded and 604 taken prisoner, and also that 507 Australians were taken prisoner between 28 March 1941 and the investment of Tobruk, and 467 more were taken during the siege.

Maritime losses were 469 British and Australian naval personnel, together with 70 merchant mariners (655 men in all), and 186 British and Australian personnel wounded, together with 55 merchant mariners (125 in all).

The British lost 88 men killed, 406 men wounded and 15 men killed for a total of 509 losses while the Australian 9^th Division led the defence, while the Indian losses in the same period were one man killed and 25 men wounded. Later arrivals, the Poles lost 22 men killed, 82 men wounded and three taken prisoner. Collation of these figures gives a total of 855 men killed, 2,487 men wounded 494 men missing, and the addition of the 70^th Division’s 2,153 casualties gives an overall total of 5,989 losses in the land forces.

Italian casualties from 15 February to 18 November were 1,130 men killed, 4,255 wounded and 3,851 missing. Libyan losses were 184 men killed, and the German losses were about 538 men killed, 1,657 wounded, about 681 missing. Between 74 and 150 Axis aircraft were shot down.