RN Caio Duilio

Caio Duilio belonged to the last generation of Italian dreadnoughts. Laid down in February 1912, launched on 24 April 1913 and completed in May 1916, she and her sister Andrea Doria carried a main battery of thirteen 305 mm guns in a mixture of triple and twin turrets, including one mounted amidships in the fashion of the day.

Her first war gave her almost nothing to do. The Adriatic of 1915–18 was a sea of mines, submarines and torpedo boats in which neither Italy nor Austria-Hungary was willing to risk its capital ships, and the Duilio spent the conflict swinging at anchor at Taranto and Corfu. Only two ships of the class were completed — she and the Andrea Doria — and both emerged in 1918 undamaged, unblooded and, within a decade, obsolete: the naval treaties of the 1920s froze new construction, and the fleet Italy had was the fleet it would keep.

Italy’s answer to obsolescence was not to scrap the old battleships but to rebuild them, and between 1937 and 1940 the Duilio was taken apart and put back together as something close to a new ship. The hull was lengthened to roughly 186.9 m, new machinery of about 75,000 shp replaced the original plant for a speed near 26 knots, and the underwater protection was rebuilt around the Pugliese system of absorption cylinders.

The gunnery changed even more radically. The amidships turret was removed altogether, and the ten remaining 305 mm guns were bored out to 320 mm — two triple turrets and two twin — while a new secondary battery of twelve 135 mm guns and an anti-aircraft outfit of ten 90 mm went in. She recommissioned in July 1940, a month after Italy entered the war, as a fast, well-armed and comprehensively modernised battleship built on a hull laid down before the First World War.

On the night of 11–12 November 1940 the Royal Navy did to the Italian battle fleet what Italy had spent three years and a great deal of money preparing it to avoid. Twenty-one Fairey Swordfish flying from HMS Illustrious attacked the fleet at anchor at Taranto in two waves. The harbour was thought too shallow for aerial torpedoes — the reason the Italian anti-torpedo nets did not reach the bottom — and the British had modified their weapons to run in it.

The Duilio was hit by one torpedo in the bow. It tore open the hull and flooded the forward magazines, and she was run aground to keep her from sinking at her moorings. Three battleships were disabled in a single night: the Littorio took three torpedoes, the Conte di Cavour one that put her out of the war for good, and the Duilio the hit that beached her — all for the loss of two Swordfish. Half the Italian battle line was sitting on the bottom of its own harbour, and every navy in the world took note, including one that would apply the lesson thirteen months later at Pearl Harbor.

Unlike the Cavour, the Duilio was worth saving. She was refloated, patched, and repaired over roughly five months — some accounts say closer to seven — and was back in service by May 1941, this time as flagship of the 1st Battle Squadron. For a fleet that had lost a third of its battle line in one night and had no capacity to replace it, the recovery of a modern-gunned battleship mattered a great deal.

What she came back to, though, was a different war from the one she had been rebuilt for. There would be no line-of-battle engagement in which those ten 320 mm guns settled the Mediterranean. The war Italy actually had to fight was a supply war, and the Duilio’s value was now measured in tonnage delivered to North Africa rather than in enemy battleships sunk.

From mid-1941 she worked as heavy escort for the convoys that kept the Axis armies in Libya supplied — operations M41, M42, M43, T18 and K7 among them. It was unglamorous, dangerous work and it was the decisive campaign of the Mediterranean war: the ships she was covering carried the fuel, ammunition and tanks on which Rommel’s offensives depended, and the Royal Navy and the RAF hunted them the whole way from the Italian ports to Tripoli and Benghazi. A battleship escorting a supply convoy was an admission of how badly those cargoes were needed.

On 17 December 1941 her convoy operation, M42, brought on the First Battle of Sirte, when British forces ran into the Italian escort. The Duilio’s group was too far off to engage, and the battle was fought and broken off by other ships — a fair summary of her second war. She was repeatedly at sea where it mattered and rarely in a position to fire her main battery at an enemy.

What finally stopped her was not the enemy but the fuel bunkers. By 1942 Italy’s oil shortage had immobilised most of the surface fleet: the ships existed, were manned and were combat-worthy, and there was nothing to move them with. The Duilio spent the rest of the war’s Italian phase largely inactive, a battleship kept in being because scrapping her would have conceded something, and unusable because the oil was not there.

In September 1943, on the armistice, she sailed with the fleet to Malta and was interned — the surrender voyage on which the Roma was sunk by a German guided bomb. The Allies allowed her back to Italian waters in 1944. She had survived two world wars, one rebuilding and one torpedo.

The Duilio’s post-war career outlasted most of her contemporaries’: she was fleet flagship from 1 May 1947 to 10 November 1949, based at Taranto — the harbour where she had been beached — before moving to La Spezia in 1953 and out of active service. She was stricken on 15 September 1956 and sold for scrap the following year, forty-three years after her launch.

The judgement on her is really a judgement on the policy that produced her. Rebuilding four elderly dreadnoughts — the two Doria-class ships and the two Cavours — consumed yards, guns and money on a scale approaching new construction, and delivered ships that were fast and well-armed but could not stand in the line against a modern battleship. Set against the Littorio class being built at the same time and in the same yards, the reconstruction programme bought the Regia Marina numbers rather than strength. Taranto showed how quickly numbers could be taken away: one night, twenty-one obsolete-looking biplanes, and three of those expensively rebuilt ships were out of the war.

• Roger Chesneau (ed.), Conway’s All the World’s Fighting Ships 1922–1946 (Conway Maritime Press).
• Aldo Fraccaroli, Italian Warships of World War II (Ian Allan).
• Thomas P. Lowry & John W. G. Wellham, The Attack on Taranto (Stackpole Books).