Clash in the Strait of Otranto

Before dawn on 15 May 1917 three Austro-Hungarian light cruisers under Captain Miklós Horthy burst in among the British drifters guarding the anti-submarine nets in the Strait of Otranto. In less than two hours they sank fourteen of them. On the way back they were intercepted by British and Italian ships from Brindisi, and the largest surface battle in the Adriatic of the whole war was fought. The British chronology of the war describes it briefly as an action between Austrian and British light forces in which 14 British drifters were sunk. On the Allied side, however, the commander was an Italian, Rear-Admiral Alfredo Acton, and Italian and French ships also took part.

The barrage and Horthy’s plan

The Strait of Otranto, between the “heel” of Italy and Albania, is about 40 nautical miles wide. From 1915 the Allies tried to use it to close the exit from the Adriatic to the German and Austro-Hungarian submarines which sailed into the Mediterranean from their bases at Pola and Cattaro (Kotor). The main part of the barrage consisted of drifters, steam fishing boats, mostly Scottish, with civilian skippers and fishermen enrolled in the naval reserve. Each trailed long indicator nets that were meant to entangle a submerged submarine or at least betray its presence. They were armed with single small guns. In January 1917 the inter-Allied naval conference in London concluded that the barrage needed better protection, but in May the drifters were still alone in the strait, while the warships waited at Brindisi and patrolled north of them.

The Austrians had raided the drifters before. Most often it was done by destroyers, and in July 1916 Horthy in the cruiser Novara sank two of them. The same officer who in December 1915 had shelled the Albanian coast had been preparing a much bigger raid since February 1917. It was to involve all three of the fleet’s fastest cruisers, Novara, Helgoland and Saida. Each had nine 100 mm guns. Their mainmasts were cut down so that in the dark they would resemble large British destroyers. Meanwhile the destroyers Csepel and Balaton were to divert the enemy’s attention with a raid off the Albanian coast. Two Austro-Hungarian submarines waited near the strait, and off Brindisi the German UC-25, which laid mines at the harbour entrance. In reserve at Cattaro lay the armoured cruiser Sankt Georg with destroyers and torpedo boats, and if needed also the old coastal defence ship Budapest. The cruisers put to sea on the evening of 14 May.

Slaughter of the drifters

That night 47 drifters were on station in the strait. The cruisers passed through their line unrecognised and at about half past three in the morning, Austrian time, each in its own sector, opened fire. The Austrians often first called on the crews to abandon their boats and only then fired. Not all the fishermen fled. Skipper Joseph Watt of the drifter Gowan Lee ordered his boat to carry on and return fire with its single gun. His boat was badly damaged but stayed afloat, and Watt received the Victoria Cross for this fight. By dawn the cruisers had sunk 14 drifters and damaged several more. They took 72 British seamen prisoner. According to British casualty lists, a dozen or so men of the boats’ crews were killed.

Meanwhile Csepel and Balaton came upon a small Italian convoy off Albania, sailing from Gallipoli in Apulia to Valona. Its escort, the old destroyer Borea, approached to find out who the strange ships were and was fired on at close range. Shells pierced her steam pipe and hull, she stopped and soon afterwards sank. Eleven of her crew were killed. Balaton set two of the three steamers on fire. Carroccio, carrying ammunition, sank, while Verità, abandoned by her crew, stayed afloat and later reached port, although some accounts state that both sank.

The pursuit

Only now did Brindisi learn what was happening. Rear-Admiral Acton, commander of the Italian scout cruiser division, went aboard the British light cruiser Dartmouth and, together with the cruiser Bristol, the Italian scout cruiser Aquila and four Italian destroyers, set off north to cut off the Austrians’ way home. Earlier a group patrolling in the north, led by the Italian Carlo Mirabello with three French destroyers, had clashed with Horthy’s cruisers, but it was too weak and could only shadow them. At about 8 a.m. Aquila ran into the returning Csepel and Balaton. A shell from Csepel hit her boiler room and disabled her, and both Austrian destroyers escaped under the cover of the coastal batteries at Durrës.

At about 9 a.m. smoke from Horthy’s cruisers was sighted from Bristol. The British had the advantage in firepower: Dartmouth had eight 152 mm guns, while the Austrians had only lighter 100 mm guns. The faster Dartmouth pulled ahead and soon hit Novara. The Austrians laid a smoke screen and turned to close to a range at which their guns could be effective, and hit Dartmouth several times. Seaplanes of both sides circled over the ships. Italian aircraft dropped bombs on Helgoland but missed. On Novara the first officer was killed, and a shell that exploded by the bridge badly wounded Horthy. He continued to command for a time, until he lost consciousness. The ship was taken over by the gunnery officer Stanislaus (Stanisław) Witkowski, according to Polish accounts of Polish descent. Further hits damaged Novara’s feed pumps and steam pipes, and at about 11 a.m. she came to a stop.

Then Sankt Georg with destroyers, summoned to help from Cattaro, appeared on the horizon. Acton withdrew for a moment to gather his ships and did not realise that Novara had lost power. This pause was enough for Saida to take her in tow, while Helgoland covered both ships. When at about noon Acton understood Novara’s plight, the Sankt Georg group was already too close, and the Italian did not want to be drawn under the guns and minefields off Cattaro. He broke off the pursuit. One of the Italian destroyers misread a signal and launched a torpedo attack on its own, but the fire of the three cruisers drove it off. All the Austro-Hungarian ships returned to Cattaro.

The day ended even worse for the Allies. On the way back to Brindisi Dartmouth was torpedoed by UC-25, lying in wait there under Kapitänleutnant Johannes Feldkirchner. She was briefly abandoned, but was then towed into port. According to British casualty lists, eight men were killed on board in the battle and by the torpedo, including Commander Robert Fane. The French destroyer Boutefeu, which had left Brindisi to hunt the submarine, struck one of its mines, broke in two and sank in less than two minutes. According to French sources 11 sailors were killed and more than 70 were rescued by Italian torpedo boats.

Outcome

Tactically the victory went to the Austrians. Without losing a single ship they sank 14 drifters, the destroyer Borea and an ammunition ship, and the German submarine added a badly damaged Dartmouth and the sunken Boutefeu. According to various accounts they themselves had a dozen or so killed, mostly on Novara, which had to be sent for repair. The wounded Horthy became a hero in Austria-Hungary.

Strategically the battle changed little. The drifter barrage did not stop the submarines anyway. Each boat covered roughly half a nautical mile, and all of them together closed little more than half the width of the strait. Submarines usually passed through without much difficulty. After the raid the British decided that until there were enough destroyers to protect them, the drifters could not stay in the strait at night, and from then on they were withdrawn before dusk. The Austrians had thus risked their three best cruisers for an objective of little importance. The Allies, for their part, had a more serious problem: throughout the Mediterranean submarines were sinking more and more ships in the spring of 1917, and escorts were still in short supply, even though Japanese destroyers had joined them in April.