The 'Capture of Tobruk' was a battle fought between British-led and Italian forces as part of 'Compass' (i), the first major offensive of Lieutenant General R. N. O’Connor’s Western Desert Force in the 'Campaign for the Western Desert' (6/22 January 1941).

After defeating the Italians in the 'Battle of Bardia', Major General I. Mackay’s Australian 6^th Division and Major General Michael O’M. Creagh’s British 7^th Armoured Division pressed forward and established contact with the Italian garrison of Tobruk on 6 January. The Italians had fortified Tobruk, their only port facility in the eastern part of Cyrenaica, before the war but after being routed at the 'Attack on Nibeiwa', the 'Battle of Sidi Barrani' and the 'Battle of Bardia', Generale di Corpo d’Armata Giuseppe Tellera’s 10a Armata had lost eight of its nine divisions and had available for the defence of Tobruk only Generale di Divisione Vincenzo Della Mura’s 61a Divisione fanteria 'Sirte' and a miscellany of stragglers from other formations and units.

In September 1940 the Italian 'Operazione 'E'' invasion of Egypt had begun but come to a halt a mere 62 miles (100 km) at Sidi Barrani, where the Italians dug in. At first the British prepared to resist an Italian advance on Mersa Matruh, but when this did not materialise the British planned a major raid by the Western Desert Force, with the possibility of exploiting success, on the Italian positions around Sidi Barrani. The raid was 'Compass' (i), which began on 9 December 1940 with the surprise 'Attack on Nibeiwa' where the Italian brigade-sized Raggruppamento 'Maletti', which was the only Italian armoured formation in Egypt, was destroyed. On 10 December the Western Desert Force engaged the three divisions of Generale di Corpo d’Armata Sebastiano Gallina’s Corpo d’Armata libico and Generale di Brigata Giuseppe Amico’s 64a Divisione fanteria 'Catanzaro' in the 'Battle of Sidi Barrani' and defeated them by 11 December.

With Generale di Brigata Alessandro Deguidi’s 63a Divisione fanteria 'Cirene', which was the last Italian division on Egyptian soil, retreating towards Libya, the 7^th Armoured Division pressed on and by 15 December had cut the road between Bardia and Tobruk. At Bardia the Italians had concentrated Generale di Divisione Annibale Bergonzoli’s XXIII Corpo d’Armata, comprising Generale di Divisione Francesco Antonelli’s 1a CCNN Divisione '23 Marzo', Generale di Divisione Francesco Argentino’s 2a CCNN Divisione '28 Ottobre', Generale di Divisione Ruggero Tracchia’s 62a Divisione fanteria 'Marmarica' and Generale di Brigata Giuseppe Amico’s 63a Divisione fanteria 'Cirene'. Other units were four light tank battalions, the remnants of the 64a Divisione fanteria 'Catanzaro', and the XXI Corpo d’Armata's artillery regiment. After careful preparation the British attacked and defeated the Italian defenders between 3 and January 1941.

On the morning of the latter day, as Australian forces were mopping up the southern cauldron at Bardia, General Sir Archibald Wavell, the commander-in-chief in the Middle East, ordered Brigadier H. E. Russell’s 7^th Armoured Brigade of Creagh’s 7^th Armoured Division to advance to the west, bypass Tobruk and thereby cut off this vitally important Italian facility. By 6 January the brigade had reached El Adem, and by 7 January the bulk of the British forces had arrived in the area and isolated Tobruk. Brigadier H. C. H. Robertson’s Australian 19^th Brigade placed itself opposite the eastern defences of Tobruk and Brigadier A. S. Allen’s Australian 16^th Brigade took over on the western side. The 4^th Armoured Brigade moved to the west of the city, the 7^th Support Group blocked the western exits and the 7^th Armoured Brigade screened the force from interference from the west.

After the encirclement of Tobruk, Maresciallo d’Italia Rodolfo Graziani, the commander-in-chief of the Italian forces in North Africa, informed Benito Mussolini, the Italian dictator, that 'This morning the investment of the position by enemy armoured vehicles has begun. After which the various episodes of the new drama are easily predictable.' Graziani informed Mussolini that the 34-mile (54-km) Tobruk perimeter was manned by only 22,000 men with 340 pieces of artillery, totals wholly inadequate for the task. On 9 January, Graziani informed the garrison commander, Generale di Divisione Enrico Pitassi Mannella, that there would be no attempt at relief. Graziani ordered Tellera to fall back with Generale di Divisione Guido Della Bona’s 60a Divisione fanteria 'Sabratha', his last division, to a line between Derna and Berta, while directing Generale di Brigata Valentino Babini’s Raggruppamento 'Babini', a special armoured brigade, to Mechili. After being informed by Graziani that he was on his own, Mannella ordered the destruction of the bridges at Sidi Daud on the Bardia road and at Wadi es Sahel on the Derna road.

Although Pitassi Mannella had 32 L3/35 tankettes and 39 M11/39 medium tanks, only seven of the latter were operational and in three weeks of attempts to repair the M11/39 machines only three were serviceable enough to move in an engagement. After it had become obvious in the autumn of 1940 that the L3/35 was obsolete and the M11/39 badly designed and prone to mechanical failure, the XXI Battaglione di carri armati (leggeri) and part of the I Battaglione di carri armati (medio) had departed for Benghazi to be re-equipped with the new M13/40 medium tank. Pitassi Mannella had received no spares or fuel for the tanks and had the lightly armed and therefore had the thinly armoured L3/35 tankettes and the M11/39 medium tanks buried in the sand as strongpoints.

Pitassi Mannella divided the Italian defensive perimeter into two sectors, five sub-sectors and 16 strongpoints. Commanded by Generale di Divisione Umberto Barberis, the Eastern Sector comprised Subsector A, from the sea to Bir Junes to block the road from Bardia, with four strongpoints, and Subsector B to block the road from El Adem, with two strongpoints. The first line of the Eastern Sector was manned by the troops of the Guardia alla Frontiera reinforced with four infantry companies of the 69o Reggimento. Expecting the main attack from this direction, Pitassi Mannella established a second line of defence between 2.5 and 3.7 miles (2 and 4 km) behind the strongpoints, based on a small hill at the junction of the El Adem and Bardia roads. On this second line, under command of the 4o Reggimento Carri, every available tank was dug in as the core of a strongpoint, and between this position and the sea the 3/69o Reggimento also dug in.

Commanded by Generale di Divisione Vincenzo Della Mura, the Western Sector comprised Subsector A in the desert to the south of Tobruk with four strongpoints, Subsector B to block the road from Acroma with three strongpoints, and Subsector C to block the road from Derna with three strongpoints. Subsectors A and B were each defended by one battalion of the 70o Reggimento, while the 'Blackshirt' Battaglione 'Volontari della Libia' held Subsector C. Behind the first line of defence were five strongpoints manned by the 3/70o Reggimento, which doubled as the reserve unit for the three battalions in the first line. The 69o Reggimento's commander was allocated all the reserves Pitassi Mannella could muster, namely an understrength tank company with seven M11/39 machines and two extemporised units each comprising one Bersaglieri motorcycle company, one infantry company, one machine gun platoon, one anti-tank platoon and one anti-aircraft section. In front of the strongpoints 11 miles (18 km) of anti-tank ditch were cleared, and 7,000 tripwire mines and 16,000 pressure mines were laid. To offset the paucity of anti-tank mines, Pitassi Mannella had 2,200 26-lb (12-kg) bombs and 800 33-lb (15-kg) bombs, left by the Regia Aeronautica, buried upright in the desert, in the hope that a British tank passing over them would trigger the impact fuse.

Pitassi Mannella organised the artillery into three groups, two for the Eastern Sector with 123 guns and one for the Western Sector with 97. Assuming correctly that the British-led forces would attack from the south, Pitassi Mannella sent into the area the II/43o Reggimento di Artiglieri and III/55o Reggimento di Artiglieria groups with 75-mm (2.95-in) 75/27 modello 11 field guns, and the CV/25o Gruppo and CXXX/25o Gruppo with 149-mm (5.87-in) 149/13 modello 14 heavy field howitzers and one battery of the XV Gruppo with 75-mm (2.95-in) 75/46 modello 34 anti-aircraft guns for service in the anti-tank role. For long-range artillery fire, Pitassi Mannella relied on the four 254- and eight 190-mm (10- and 7.5-in) guns of the old cruiser San Giorgio in Tobruk harbour. Two Regia Marina shore batteries had twin 120-mm (4.72-in) naval guns and two mobile 149-mm (5.87-in) heavy guns of the Guardia alla Frontiera.

Lacking air reconnaissance, Pitassi Mannella was unaware of the British artillery positions, and as most of the British artillery outranged that of the Italians, there was little chance of effective Italian counterbattery fire. Pitassi Mannella decided to employ every gun capable of direct fire in the anti-tank role, and managed to assemble 110 anti-tank guns in the form of 32 37-mm guns in the buried M11/39 tanks, 43 47/32 modello 1935 anti-tank guns, 13 65-mm (2.56-in) 65/17 modello 13 mountain guns, 11 75-mm (2.95-in) 75/27 modello 11 field guns, 10 77-mm (3.03-in) 77/28 modello 5 field guns and one 76-mm (2.99-in) 76/40 modello 16 naval gun found in the naval stores; armour-piercing ammunition was available for only the 37-mm and 47-mm anti-tank guns.

After surrounding Tobruk, the Western Desert Force had exhausted the ample quantities of Italian supplies captured at Capuzzo and Sollum, and O’Connor directed that the supplies flowing through the port of Sollum (350 tons per day early in January and 500 tons per day late in the month) to the 10^th and 11^th Field Depots he had established about 43 miles (70 km) to the east of Tobruk. Concerned mostly about his shortages of fuel and other supplies for the offensive after the fall of Tobruk, O’Connor delayed the attack to accumulate more supplies. As the 7^th Armoured Division had suffered greater losses than the Australian 6^th Division, O’Connor decided that the Australians would lead the attack. The two most depleted units, the 8^th King’s Royal Irish Hussars and the 6^th Royal Tank Regiment, were withdrawn and their equipment distributed to the other four regiments of the armoured brigades. The first wave of the attack was to be based on Allen’s Australian 16^th Brigade and the 7^th Royal Tank Regiment, followed by Brigadier S. G. Savige’s Australian 17^th Brigade and Robertson’s Australian 19^th Brigade. The 7^th Armoured Division would attack along the western side of the Italian perimeter to pin its defenders. On 19 January aircraft of the Royal Air Force dropped leaflets calling on the Italians to surrender, but Pitassi Mannella ignored all such blandishments.

From 00.00 to 02.00 on 21 January, the monitor Terror and three smaller warships bombarded Tobruk, while destroyers waited farther offshore to attack San Giorgio should she attempt to escape. For the rest of the night Vickers Wellington twin-engined medium bombers attacked port installations and defensive positions, and drowned the sound of the British tanks assembling for the attack.

At 05.40, the British artillery opened fire along the entire line, concentrating on a rectangular area measuring about 2,185 yards (2000 m) by 765 to 875 yards (700 to 800 m) where Subsectors A and B of the Eastern Sector met. Under cover of night Australian sappers and the British artillery fire cleared a path through the thin Italian minefield in the area. At first light the Australian 2/3^rd Battalion attacked and, within the hour, had created a breach 1.25 miles (2 km) wide. At 07.00, 18 Matilda II tanks passed through this breach, three of them then veering to the left with the Australian 2/3^rd Battalion and another three veering to the right with the Australian 2/1^st Battalion to expand the breach. At the same time, the other 12 Matilda tanks advanced with the Australian 2/2^nd Battalion toward Tobruk. The first unit to be overrun by the Australian 2/2^nd Battalion was the CV/25^th Gruppo, which had been offered no time to lay its guns for direct fire before it was overrun.

The Italians' lack of radios proved to be a severe disadvantage, and the telephone lines on which they perforce relied had been cut by the British aerial and artillery bombardment, so Pitassi Mannella received notice of the British attack only at about 08.30 to 08.45 from a despatch rider. By 09.10, the Australian 2/2^nd Battalion had reach Sidi Mahmud and the Australian 2/1^st Battalion was at Sidi Daud; the Australian 17^th Brigade, with the 2/6^th Battalion and 2/7^th Battalion, had captured the Italian artillery positions between the two points. By 10.30, the Australians had overrun four of the Italian strongpoints and destroyed six of the 10 artillery groups in the area. At 08.30, the Australian 19^th Brigade supported by A Squadron of the Australian 6^th Division Cavalry Regiment had set off toward the 4o Reggimento Carri. The Australian brigade was supported by 78 field guns, which leapfrogged 220 yards (200 m) forward every two minutes. The Australian 19^th Brigade struck the 3/69o Reggimento and quickly overran it. A Bersaglieri company and three M11/39 tanks which attempted to plug the gap in the second line were defeated within minutes, the three M11/39 machines being knocked out.

By 11.50, Pitassi Mannella had informed Graziani that the Eastern Sector had been destroyed and only isolated positions were still holding. All Graziani could do was to send three Fiat CR.30 single-engined biplane fighters to Tobruk, and these were quickly intercepted and shot down by RAF fighters. Between 12.00 and 14.00, the Australian 19^th Brigade attacked the position of the 4o Reggimento Carri with such ferocity that 70% of the officers, including both battalion commanders, and 50% of the troops were killed in action. During the day, Bristol Blenheim twin-engined light bombers of Nos 55 and 113 Squadrons flew 56 sorties against Tobruk, and the Gloster Gladiator single-engined biplane and Hawker Hurricane single-engined monoplane fighters of No. 3 Squadron RAAF, No. 73 Squadron RAF and No. 274 Squadron RAF patrolled to the west.

At 13.00, Pitassi Mannella ordered the mobile reserve, with the seven operational M11/39 tanks, to attack the Australian left flank under an artillery barrage. Two Australian anti-tank guns and two tanks destroyed five of the seven M11/39 tanks, and when Australian infantry pushed forward the mobile reserve surrendered. At 16.00, the Australian 2/8^th Battalion attacked the Pilastrino position, while the Australian 2/4^th Battalion had reached and surrounded the Italian headquarters at the abandoned Fort Solaro. Pitassi Mannella and his staff retreated into the cellars but by 18.30 the Italian commander had ordered his staff to surrender. At the same time the Australian 6^th Divisional Cavalry Regiment had reached the outskirts of Tobruk but then been stopped by the fire of San Giorgio. Men of the Australian 2/4^th Battalion moved down the cliffs and used 3-in (76.2-mm) mortars against San Giorgio. Having lost contact with forces outside of Tobruk, Contrammiraglio Massimiliano Vietina organised the defence of the harbour with the few men at his disposal. Graziani had denied the admiral’s request to make a sacrificial attack on the British ships outside the harbour, and Vietina began systematically to destroy the harbour and its stores.

By the fall of night, half of the Tobruk fortified area had been captured and at 04.15 on 22 January, Vietina ordered Capitano di Vascello Stefano Pugliese to detonate San Giorgio's magazines and thereby deny the ship to the British. Mackay ordered a general advance for the morning of 22 January, and at 08.30 Vietina surrendered to Robertson, the commander of the Australian 19^th Brigade, followed shortly after this by Della Mura, who surrendered with the remnants of the Pilastrino position. by 16.00 the last strongpoint had surrendered and Tobruk had fallen.

Most of the Italian demolitions had been of stores rather than installations. The Mediterranean Fleet’s Inshore Squadron began minesweeping immediately and opened the port on 24 January.

The Italians had suffered more than 24,000 casualties: 18 officers and 750 other ranks had been killed, 30 officers and 2,250 other ranks had been wounded, and more than 20,000 men had been taken prisoner. The British-led force captured 208 pieces of artillery and 87 tanks, and the XIII Corps, as the Western Desert Force was renamed, had suffered 400 casualties, 355 of them Australian.

By the time of the Italian surrender, O’Connor’s divisions had already pressed farther to the west, the 7^th Armoured Division reaching Mechili and fighting the 'Action at Mechili' on 24 January, while the Australian 6^th Division had reached the Italian forward positions at Derna on the same day.