When Italy declared war in June 1940, the Regia Marina was one of the largest navies in the world but it was restricted to the Mediterranean. The British Empire possessed enough resources and naval might to maintain a strong presence in the area and replace most losses by redeploying ships. This led to caution by the Italian command and a tendency to avoid conflict. Control of the Mediterranean was disputed by the Regia Marina the Royal Navy and their allies. The sea was vital for the supply of the Italian and German forces in North Africa, as well as the maintenance of Malta as a British offensive base. Without Malta, Britain could not intercept Italian convoys to prevent the supply of Axis forces.
The possession of radar and the breaking of Italian codes, particularly the Boris Hagelin C38 cipher machine used by the Regia Marina, further contributed to British success. In November 1941, the supply of the Axis forces in Libya from Italy, had been interrupted by Force K, which had destroyed several Italian convoys (most notably the Duisburg convoy) and the loss of nearly 70 percent of the supplies sent to Libya, including 92 percent of the fuel. Force K based at Malta, and ships from Alexandria, intercepted an Axis convoy Maritza and Procida, escorted by two Italian torpedo boats, sailing from Greece to Benghazi of on 24 November. The convoy was about 100 nmi (120 mi; 190 km) west of Crete when the merchant ships were sunk by two British cruisers and two destroyers, the torpedo boats making off once it was certain that the ships were doomed. The loss of the cargoes led the German command to report that the fuel situation of the Luftwaffe in North Africa was critical.
The Italian and German forces in North Africa, facing Operation Crusader, a new Allied offensive, were in urgent need of fuel and ammunitions. Supermarina (the general staff of the Royal Italian Navy), at the request of Comando Supremo (supreme command of the Italian armed forces), developed an emergency plan to shift supplies using warships. The Alberico da Barbiano and Alberto di Giussano, light cruisers of the 4th Cruiser Division and commanded by ammiraglio di divisione (divisional admiral) Antonino Toscano, were fast and too lightly armored for employment with the battle fleet and were selected for this role.
Da Barbiano (Toscano’s flagship) and Di Giussano left Taranto at 8:15 on 5 December 1941, reached Brindisi at 17:50 and there loaded about 50 t (49 long tons) of supplies, then proceeded to Palermo on 8 December, where they loaded another 22 t (22 long tons) of aviation fuel to alleviate a shortage in Libya, which would prevent aircraft from escorting supply convoys. The fuel, contained in unsealed barrels, was placed on the stern deck, creating a grave risk of fire from British gunfire and from the discharge of the ships’ own guns, preventing the use of the stern turrets unless the fuel was jettisoned. The two cruisers sailed unescorted from Palermo at 17:20 on 9 December, heading for Tripoli. At 22:56, when north of Pantelleria, they were spotted by a British reconnaissance aircraft, which had been directed to the area by Ultra intercepts, and which started to shadow them. At 23:55, Toscano (who was at that time in the middle of the Sicilian Channel) decided to turn back to base, as the surprise required for the success of the mission had vanished, much British radio traffic foreshadowed air attack, and worsening sea conditions would delay the ships, further exposing them to British attacks. Da Barbiano and Di Giussano reached Palermo at 8:20 on 10 December, after overcoming a British air attack off Marettimo. Toscano was heavily criticized by the Supermarina for his decision to abort the mission.
Convoy M. 41, was planned for 13 December but air cover by aircraft based in Libya would be impossible unless they received fuel from Italy. On 12 December it was decided that the 4th Division would attempt again the trip to Tripoli. The cruiser Bande Nere was to join Da Barbiano and Di Giussano to carry more supplies but she was prevented from sailing by a breakdown and the cargo was transferred to the other two cruisers. Da Barbiano and Di Giussano were loaded with 100 t (98 long tons) of aviation fuel, 250 t (246 long tons) of gasoline, 600 t (591 long tons) of naphtha, 900 t (886 long tons) of food and 135 ratings on passage to Tripoli. The stern of Da Barbiano (and to a lesser extent, Di Giussano) was packed with fuel barrels, so thickly that it was not possible to traverse the guns; Toscano held a briefing with his staff and officers from both ships, where it was decided that, in case of encounter with enemy ships, the barrels would be thrown overboard to enable the ships to open fire. Da Barbiano, Di Giussano and their only escort, the Spica-class torpedo boat Cigno (a second torpedo boat, Climene, was left in the port due to a breakdown), sailed from Palermo at 18:10 on 12 December. The 4th Division was ordered to pass north-west of the Aegadian Islands and then head for Cape Bon and follow the Tunisian coast; the ships would keep a speed of 22–23 kn (25–26 mph; 41–43 km/h) to conserve fuel and deliver it at Tripoli. Air cover, air reconnaissance and defensive MAS ambushes were planned to safeguard the convoy.
The British 4th Destroyer Flotilla, consisting of the destroyers HMS Sikh, HMS Maori, HMS Legion and the Dutch destroyer HNLMS Isaac Sweers, (Commander G. H. Stokes), had departed Gibraltar on 11 December, to join the Mediterranean Fleet at Alexandria. By 8 December, the British had de-coded Italian C-38 wireless signals about the Italian supply operation and its course for Tripoli. The RAF sent a Wellington bomber on a reconnaissance sortie to sight the ships as a deception and on 12 December, the 4th Destroyer Flotilla, heading east from Gibraltar towards the Italian ships, was ordered to increase speed to 30 kn (35 mph; 56 km/h) and intercept. In the afternoon of 12 December, a [[CANT Z.1007#Z�07bis|CANT Z.1007 bis]] of the Regia Aeronautica spotted the four destroyers heading east at an estimated speed of 20 kn (23 mph; 37 km/h), 60 mi (97 km) off Algiers; Supermarina was immediately informed but calculated that, even in the case the destroyers would increase their speed to 28 kn (32 mph; 52 km/h), they would not reach Cape Bon until around 03:00 on 13 December, about one hour after the 4th Division, so Toscano (who learned of the sighting while he was still in harbour) was not ordered to increase speed or alter course to avoid them.
Following new Ultra decodes a new reconnaissance plane was sent and spotted Toscano’s ships at sunset on 12 December, after which the 4th Destroyer Flotilla was directed to intercept the two cruisers, increasing speed to 30 knots. This speed, along with a one-hour delay that the 4th Division had accrued (and that Toscano omitted to report to Supermarina), frustrated all previous Supermarina calculations about the advantage that the 4th Division would have. At 22:23 Toscano was informed that he would possibly meet “enemy steamers coming from Malta“, and at 23:15 he ordered action stations.
12/13 December, night
The 4th Destroyer Flotilla sighted the Italian cruisers near Cap Bon, at 02:30 on 13 December. At 2:45 on 13 December, seven miles off Cape Bon, the Italian ships heard the noise of a British plane (a radar-equipped Vickers Wellington, which located the ships and informed Stokes about their position), and at 3:15 they altered course to 157° to pass about a mile off Cape Bon. Five minutes later, Toscano suddenly ordered full speed ahead and to alter course to 337°, effectively reversing course; this sudden change disrupted the Italian formation, as neither Cigno (which was about two miles ahead of the cruisers) nor Di Giussano (which was following Da Barbiano in line) received the order, and while Di Giussano saw the flagship reverse course and imitated her (but remained misaligned) Cigno did not noticed the change until 3:25, when she also reversed course, but remained much behind the two cruisers.
13 December, morning
Stokes’s destroyers were just off Cape Bon by then and they had spotted the Italian ships. Arriving from astern, under the cover of darkness and using radar, the British ships sailed close inshore and surprised the Italians, who were further out to sea, by launching torpedoes from short range. The course reversal accelerated the approach between the two groups and the Allied destroyers attacked together; Sikh fired her guns and four torpedoes against Da Barbiano (less than 1,000 m (1,100 yd) distant), Legion did the same, Isaac Sweers opened fire against Di Giussano and Maori fired six torpedoes against Di Giussano. Toscano ordered full speed and to open fire (and ordered Di Giussano to increase speed to 30 kn (35 mph; 56 km/h)). Da Barbiano also started a turn to port (on orders from Captain Giorgio Rodocanacchi), but at 3.22, before her guns were able to fire (only some machine guns managed to), the cruiser was hit by a torpedo below the foremost turret, which caused her to list to port. Da Barbiano was then raked with machine gun fire, which killed or wounded many men and set fire to the fuel barrels, and was hit by a second torpedo in the engine room.
At 3.26 Maori fired two torpedoes at Da Barbiano and opened fire with her guns, hitting the bridge. The cruiser was hit soon after by another torpedo in the stern (possibly launched by Legion) and Di Giussano was also hit by a torpedo and gunfire, being left disabled. The land behind the Allied destroyers made it impossible for the Italians to see them and Di Giussano managed to fire only three salvoes. In five minutes both cruisers were disabled; Da Barbiano rapidly listed to port, while fires quickly spread all over the ship and into the sea by the floating fuel; the crew abandoned ship. At 3:35, Da Barbiano capsized and sank in a sea of flame, with Toscano, Rodocanacchi and another 532 men still aboard. Di Giussano was left dead in the water with fires raging; the crew struggled to keep the ship afloat but she also had to be abandoned, breaking in two and sinking at 4:20, with the loss of 283 men. After a brief encounter with the Dutch destroyer Isaac Sweers, Cigno rescued nearly 500 survivors; others reached the coast and another 145 men were later saved by Italian Motoscafo armato silurante motor torpedo boats; Italian losses amounted to 817 men.
Toscano’s decision to reverse course has never been fully explained, but various possibilities have been suggested. He may have decided to turn back after realizing that he had been spotted by aircraft, as he did on 9 December; however, a course towards the Aegadian islands would have made more sense, instead of the north-westerly course ordered by Toscano. The course change was ordered more than 30 minutes after the cruisers had been spotted; Toscano may have wanted to mislead the reconnaissance aircraft about his real course, wait for it to leave and then turn again for Tripoli. He may have thought, from the aircraft noise, that torpedo bombers were coming, and he wanted to get into waters farther away from the shore and from Italian minefields in order to gain freedom of manoeuvre. Toscano ordered his gunners to stand by; he may have known that Allied destroyers were astern of his ships, and he wanted to avoid presenting his stern to them because his aft turrets were obstructed by the fuel barrels.
- “Antonino Toscano – Marina Militare”. www marina difesa it. 2017. Retrieved 23 November 2017.
- Cocchia, Aldo (1962). La difesa del traffico con l’Africa Settentrionale: dal 1° ottobre 1941 al 30 settembre 1942 [The Defence of Traffic with North Africa from 1 October 1941 to 30 September 1942]. Marina italiana nella seconda guerra mondiale (in Italian). VII. Roma: Ufficio Storico della Marina Militare. OCLC 221140047.
- Ghisotti, A. (21 July 2010). “Il ritrovamento del relitto dell’incrociatore italiano da Barbiano” [The Discovery of the Wreck of the Italian Cruiser Barbiano] (in Italian). Focus magazine. Retrieved 23 November 2017.
- Greene, J.; Massignani, A. (2002) . The Naval War in the Mediterranean 1940–1943 (pbk. ed.). Rochester: Chatham. ISBN 978-1-86176-190-3.
- Hinsley, F. H. (1994) . British Intelligence in the Second World War. Its influence on Strategy and Operations. History of the Second World War. abridged (2nd rev. ed.). London: HMSO. ISBN 978-0-11-630961-7.
- Roskill, S. W. (1957) . Butler, J. R. M. (ed.). The War at Sea 1939–1945: The Defensive. History of the Second World War United Kingdom Military Series. I (4th impr. ed.). London: HMSO. OCLC 881709135. Retrieved 14 March 2016.
- Santoni, Alberto (1981). Il vero traditore: il ruolo documentato di ULTRA nella guerra del Mediterraneo [The Real Traitor: The Documented Role of Ultra in the Mediterranean War]. Biblioteca del mare, 217: Guerra sui mari, 34 (in Italian). Milan: Mursia. OCLC 491163648.
- D’Este, Carlo (1990). World War II in the Mediterranean, 1942–1945. Major Battles and Campaigns. Chapel Hill, NC: Algonquin Books. ISBN 978-0-94557-504-7.