The 'Battle of the Duisburg Convoy', also known as the 'Battle of the Beta Convoy', was fought between Italian and British naval forces and involved an Italian convoy, its escorts and four British ships (8/9 November 1941).

The convoy was named 'Beta', but is often known as the 'Duisburg convoy' for its largest ship, and comprised seven merchant vessels carrying supplies for the Italian army, Italian civilian colonists and the Deutsches Afrika Korps in the Italian North African colony of Libya.

The Royal Navy’s Force 'K', operating from Malta, intercepted and annihilated the convoy, sinking all the merchant ships and the destroyer Fulmine without loss to itself and with almost no damage. The 'Maestrale' class destroyer Libeccio was sunk on the following day by the British submarine Upholder as the ship was recovering survivors.

The Italians were severely criticised by the German naval attaché in Rome and pressured to accept German liaison officers at the Supermarina, the headquarter of the Regia Marina, and on its ships. Italian attempts to reduce the risk of interception by British forces, then involved the despatch of ships individually, in pairs and in smaller convoys from several ports at once, but this tactic proved futile because the British were reading Italian naval codes. The next convoy was forced to return to port.

Italy’s declaration of war on France and the UK during 10 June 1940 placed warplanes of the Regia Aeronautica astride the traditional British sea route to Indian Ocean ports through the Mediterranean Sea and the Suez Canal. The access of the Regia Marina to the Axis arsenal approximately trebled the numbers of battleships, cruisers and submarines available to the Axis powers. Between September 1939 and June 1940, the British had held the eastern end of the Mediterranean Sea and France the western end, but on 25 June 1940 the fall of France ended the participation of the French navy in the Allied domination of the Mediterranean Sea. The British based a major force at each end of the Mediterranean Sea as Vice Admiral Sir James Somerville’s Force 'H' at Gibraltar and Admiral Sir Andrew Cunningham’s Mediterranean Fleet at Alexandria in northern Egypt, and also used the island of Malta in the central part of the Mediterranean Sea as a secondary but nonetheless vital base of operations. In September 1940, the Italian invasion of Egypt took place from Africa Settentrionale Italiana, as Libya was designated, leading to the capture of Sidi Barrani, and the Italian army invaded Greece in 'Esigenza 'G' during the following October.

Early in November 1940, the Italian offensive in Greece had been defeated and the Italian battleships Littorio, Conte di Cavour and Caio Duilio had been damaged by Royal Navy torpedo bombers in the 'Judgement' attack on Taranto. The ship losses of the Italian fleet now made it easier for the British to supply Malta and Greece, the latter in 'Lustre'. The Axis forces involved in the 'Campaign for the Western Desert' were supplied across the Mediterranean Sea by convoys from Italy to Libya, where Tripoli was the main destination for such convoys. Lesser ports farther to the east, including Benghazi, were also used for the delivery of men, equipment and fuel. The normal wartime route for Italian supply deliveries to Libya was about 600 mi (966 km) westward round Sicily and then hugged the coast from Tunisia eastward to Tripoli, a route selected in an effort to evade the attentions of British warplanes, surface warships and submarines from Malta. Once they had reached North Africa, Axis supplies had to be carried huge distances by road or in small consignments on coastal trading vessels, the distance from Tripoli to Benghazi being about 650 miles (1050 km).

Early in 1941, after 'Compass', the major British and commonwealth victory in north-western Egypt and Cyrenaica, the best-equipped units in the British XIII Corps were sent to Greece in 'Lustre' to assist the Greeks resist the Italian invasion and to be ready to meet an anticipated German invasion, which later materialised as 'Marita'. Adolf Hitler responded to the Italian disaster in Egypt with his Führerweisung Nr 22 directive of 11 January ordering the implementation of 'Sonnenblume' for the deployment of General Erwin Rommel’s new Deutsches Afrika Korps to Libya, as a Sperrverband (barrier detachment). The Deutsches Afrika Korps had fresh troops with better tanks, equipment and air support than the surviving Italian forces in Libya. The Axis force raided and quickly defeated the British at El Agheila on 24 March and at Mersa el Brega on 31 March, exploited the success and by 15 April, had pushed the British back to the Libyan/Egyptian border at Sollum, and laid siege the small Libyan port of Tobruk. Several Axis attempts to seize Tobruk failed and the front settled on the Egyptian border into November 1941.

Between 1 June and 31 October, British forces based at Malta sank about 220,000 tons of Axis shipping on the African convoy routes: of this total, 94,000 tons succumbed to the warships and submarines of the Royal Navy and 115,000 tons to the warplanes of the Royal Air Force and Fleet Air Arm from Malta and Egypt. Loaded Axis ships sailing to Africa comprised some 90% of these losses and the Malta-based squadrons were responsible for about 75% of ships sunk by aircraft. In October 1941 the British re-established Force 'K' as a flotilla of surface ships at Malta for the first time since April, plus a detachment of Fairey Swordfish single-engined torpedo bombers. Italian air reconnaissance discovered the ships on 21 October and cancelled sailings for Tripoli, leaving only the inferior facilities at Benghazi for the nourishment of the Axis land and air forces.

The 'Beta' convoy comprised two German vessels, the 7,889-ton Duisburg and the 3,113-ton San Marco, and three Italian vessels, the 6,339-ton Maria, 5,153-ton Sagitta and 5,180-ton Rina Corrado, together carrying 389 vehicles, 34,473 tons of munitions, fuel in barrels, and troops for the reinforcement of the Italian and German forces in Libya. Two tankers, the 7,599-ton Conte di Misurata and 6,014-ton Minatitlan, carried 17,281 tons of fuel.

A powerful escort was arranged for the convoy operation in order to counter Force 'K'. The close escort, commanded by Capitano di vascello Ugo Bisciani, comprised the 'Maestrale' class destroyers Maestrale, Grecale and Libeccio, the 'Folgore' class destroyer Fulmine, the 'Turbine' class destroyer Euro and the 'Oriani' class destroyer Alfredo Oriani. The distant escort, commanded by Ammiraglio di divisione Bruno Brivonesi, was provided by the 3a Divisione Incrociatori comprising the 'Trento' class heavy cruisers Trieste and Trento, and the 13a Flottiglia Cacciatorpediniere comprising the 'Soldati' class destroyers Granatiere, Fuciliere, Bersagliere and Alpino.

The convoy was routed to the east of Malta, since the airfields in Libya were under Axis control, rather than the usual west and along the Tunisian coast. The convoy speed was 9 kt and the distant escort had to sail a zigzag course at 16 kt. Because they overlooked the fact that British ships were equipped with radar, Brivonesi and the Supermarina were under the impression that the British ships would not be able to attack at night and therefore prepared only for attacks by aircraft.

Captain W. G. Agnew’s Force 'K' comprised two light cruisers each with a primary armament of six 6-in (152.2-mm) guns in twin turrets each and two triple 21-in (533-mm) torpedo tubes. Two destroyers from Force 'H', each with a primary armament of eight 4-in (101.6-in) guns in four twin turrets and two quadruple 21-in (533-mm) torpedo tubes, joined Force 'K' at Malta. Intended to fight at night, all of the ships were equipped with radar and the cruisers had new searchlights with better performance. The two 'Arethusa' class light cruisers were Aurora (flag) and Penelope, and the two 'L' class destroyers were Lance and Lively.

The 'Beta' convoy was the 51^st German and Italian sailing since 8 February, and departed Naples on 7 November. Force 'K' sailed on the following day, forewarned by the British success in deciphering Italian signals concerning Axis shipping movements in the Mediterranean. As camouflage for the British deciphering capability, a British reconnaissance aeroplane was despatched serendipitously to 'find' the convoy.

Force 'K' made 28 kt to the north-east of Malta, with Aurora leading the ships in line-ahead formation. The main convoy was found at about 00.00 about 155 miles (250 km) to the east of Syracuse in Sicily. There was slight moonlight to the east and the British ships took up position with the moon silhouetting the convoy. Agnew had been ordered to attack the nearest escorts first and then fire on the convoy, dealing with the other escorts as they appeared. The British ships slowed to 20 kt and the gun crews were ordered to fire steadily, with volume of fire being secondary to accuracy. As the British ships closed the convoy, radar detected more ships, assumed to be destroyers and escorts but actually the distant escort. Force 'K' sent an attack signal at 00.47, and this was received by Trieste, but jamming by Lively prevented a warning reaching the convoy; the only ships aware of the attack were 11 miles (17 km) away.

Aiming by radar, the British opened fire at about 00.58 at a range of 5,200 yards (4755 m) down to 3,000 yards (2745 m). Grecale was hit by the first three salvoes from Aurora; Lance and the 4-in (101.6-in) secondary armament of Aurora bombarded a merchant ship. Penelope engaged Maestrale, the leader of the close escort, and was on target with her first salvoes, and Lively began to shell the merchant ships three minutes later. At first, the Italians thought that they were under air attack and Maestrale's radio mast was hit. Fulmine attacked but was soon severely damaged by British gunfire, Capitano di corvetta Mario Milano losing an arm but remaining in command until his ship sank. Grecale was hit and came to a stop outside torpedo range, and was later towed back to port by Oriani. Euro, which was undamaged, came within 2,185 yards (2000 m) of the British ships but mistook them for Trieste and Trento, an error aided by the fact that the ships did not fire on her. Maestrale had been signalling for Italian ships to rally on the convoy’s port side, leading Capitano di corvetta Giuseppe Cigala Fulgosi, captain of Euro to countermand an order to launch torpedoes. Moments later, British ships opened fire but Euro was no longer in a position to attack with torpedoes. Six British shells hit Euro but at so short a range passed through without detonating but nonetheless killing about 20 members of the destroyer’s crew.

The distant escort was on the right-hand side of the convoy, steaming twice as fast, zigzagging to maintain station, and also believed that the convoy was under air attack. At 01.13 Brivonesi signalled to the Supermarina that torpedo bombers were attacking and then sailed for the point at which the British ships had first been sighted rather than their current position. When look-outs on Trieste saw the arc of shells and ships beginning to burn, the distant escort was about 5,000 yards (4570 m) distant at the end of its zigzag away from the convoy. As the escort closed on the convoy, the British ships moved beyond the glare of the burning ships and became much harder to identify. Trento fired star shells, then both Trieste and Trento opened fire at the British ships with their 8-in (203.2-mm) guns at a range of 8,750 yards (8000 m). From 01.10 to 01.25, the British warships engaged the Axis merchant vessels with shell and torpedo fire, the ships taking little evasive action. The close escort on the eastern side of the convoy moved off with Maestrale and Euro to rally, and then attacked again, the Italian salvoes having no effect and the ships then being driven off. The distant escort sighted the British again and fired a total of 207 8-in (203.2-mm) rounds, managing to straddle some of the British ships. The fires and explosions on the merchant ships obscured the British ships and Brivonesi ordered the distant escort to turn to the north at 24 kt in order to intercept them, but made no further contact. Some shells had landed close to British ships as they finished the destruction of the convoy, but these caused only splinter damage to Lively's funnel. By 01.40 the firing has ceased.

All the Axis merchant ships had sunk or were on fire and sinking. At 02.05 the British headed at high speed toward Malta, ineffectively chased by the Italian covering force and not noticing Italian salvoes at 02.07. Force 'K' had reached harbour at Malta by 13.00 that afternoon, having sunk about 39,800 tons of Axis shipping. The destroyer Libeccio was torpedoed by the submarine Upholder while rescuing some of the 704 survivors of the 'Beta' convoy. Libeccio was taken in tow by Euro but sank after an internal structural collapse. The Italian cruisers were also looking for survivors and managed to evade torpedoes.

The battle was a serious Italian defeat, in which individuals had shown exemplary bravery but the escorts had lacked co-ordination and made mistakes because of the confusion caused by the surprise and speed of the British attack and through mistaken identity. The Italians had no answer to the superior British night fighting equipment and tactics, which had revolutionised the whole nature of maritime night fighting. Technical obsolescence made an Italian attempt to counter the British at night a useless sacrifice of crews and ships. The morale of the Regia Marina suffered greatly after so formidable an escort had failed to prevent the disaster. On the day after the battle, Rommel signalled to Berlin that convoys to Libya has been suspended and that of 60,000 troops due in Benghazi, only 8,093 had arrived. Some Axis supplies arrived in ships sailing alone or in pairs, more resupply runs were undertaken by submarine, and fuel was carried by warships. Fewer convoys with more escorts and air cover were planned and four convoys sailed on 20 November.

The German naval attaché, Vizeadmiral Werner Löwisch, criticised Italian night fighting training, noting that of his 150 training sessions on the German light cruiser Leipzig, 130 had been at night. Italian ships had no night fighting equipment such as low-light-level rangefinders, and torpedo boats could not engage targets at ranges of greater than 9,840 yards (9000 m). In a report to Berlin, Konteradmiral Eberhard Weichold, the German liaison officer with the Supermarina, blamed a lack of training and accused Brivonesi of incompetence. In retrospect, the Italians had erred in assuming that a night attack by ships was unlikely; and merchant ships should have been instructed to scatter or sail away from an attack. The destroyers on the port side should not have withdrawn but attacked at once without regard for the risk of friendly fire, and the distant escort should have estimated the position of Force 'K' instead of heading toward the sighting, attacking the British as they sailed for Malta. Brivonesi was court-martialled and dismissed for not attacking, but was reinstated on 5 June 1942.

The destruction of the 'Beta' convoy had been described as 'one of the most brilliant British naval surface victories of the war' in which the British demonstrated better tactical ability, equipment and leadership, combined with luck, surprise and Italian incompetence. The Germans were outraged and wanted to foist German naval officers onto Supermarina and even Italian ships. Grossadmiral Erich Raeder, commander-in-chief of the German navy, told Adolf Hitler that 'Today the enemy has complete naval and air supremacy in the area of the German transport routes….[T]he Italians are not able to bring any major improvements in the situation, due to the oil situation and due to their own operational and tactical impotence.'

The Supermarina now had recourse to smaller, dispersed convoys and sailing convoys at the same time to mislead the British, but the British codebreakers exposed the ruses. When four ships sailed from Naples on 20 November with an escort of heavy and light cruisers, British submarines from Malta torpedoed two cruisers, forcing the convoy to turn back.