Sinking of the battleship Wien

On the night of 9/10 December 1917 two small Italian MAS torpedo boats cut through the barriers in the roadstead of Trieste and slipped unnoticed into the bay off Muggia, where two Austro-Hungarian coastal defence ships, Wien and Budapest, lay at anchor. At 2.32 a.m. both boats fired their torpedoes. Two hit Wien, which capsized and sank within a few minutes. The torpedoes fired at Budapest missed. Both boats returned to Venice without loss. The operation was led by a young naval reserve officer, Luigi Rizzo, before the war a master mariner.

Wien and Budapest were old ships of the Monarch class, built in Trieste in the 1890s. Each displaced about 5,600 tons and carried four 240 mm guns. Until mid-1917 they were based at Cattaro, and in August they were moved to Trieste. After the Italian defeat at Caporetto the front came to rest on the lower Piave, whose mouth lies a few dozen kilometres from Trieste on the other side of the gulf. On 16 November the two battleships shelled the Italian coastal batteries at Cortellazzo at the mouth of the river and, according to Austrian sources, silenced most of the guns. Counter-attacks by Italian aircraft and torpedo boats had no effect. The Italian navy therefore decided to attack them in harbour.

Through the barriers

The plan was prepared by Lieutenant-Commander Carlo Pignatti Morano di Custoza. Two boats were assigned to the task, Rizzo’s MAS 9 and MAS 13, commanded by Chief Helmsman Andrea Ferrarini. The MAS torpedo boats (PL) were small, fast motor boats carrying two torpedoes, and when approaching a target they could move almost silently on auxiliary electric motors. At about 5 p.m. on 9 December two torpedo boats towed them out of Venice and late in the evening cast them off in the middle of the Gulf of Trieste. The boats crept up to the breakwater. The entrance to the bay was closed by steel cables strung at several depths. The crews cut through them with shears for about two hours, all the while under the noses of the Austrian sentries.

When the last cable gave way, the boats entered the roadstead and separated: MAS 9 made for Wien, MAS 13 for Budapest. Rizzo closed to within a few dozen metres of the battleship and fired both torpedoes. The explosions tore a hole about 10 metres wide in Wien’s side abreast the boiler rooms. The watertight doors were open, so the water quickly flooded one compartment after another, and an attempt to correct the list by flooding tanks on the other side was useless. The ship capsized and settled on the bottom in a depth of some fifteen metres. Ferrarini’s torpedoes passed Budapest and exploded against the quay. The surprised Austrians at first thought it was an air raid and opened anti-aircraft fire. In the confusion both boats slipped out of the harbour.

Casualties and consequences

The number of dead varies with the source. Austrian figures, cited by the naval historians Erwin Sieche and Ryan Noppen, speak of 46 killed, while Italian studies give 33. Most of the crew of about 440 were saved. The Austro-Hungarian navy at once opened an inquiry. On 14 December the commandant of the Trieste naval district, Vice-Admiral Alfred von Koudelka (PL), the captains of both battleships and the commandant of the harbour defences appeared before a court martial. In January 1918 the court found that they had not taken every possible precaution, and all four lost their posts.

In Italy, which a few weeks earlier had suffered the disaster on the Isonzo and was still defending the line of the Piave, the news of a ship sunk in the enemy’s own harbour was greeted with enthusiasm. Rizzo received the Gold Medal of Military Valour, Italy’s highest gallantry award, and promotion for war merit. It was one of the boldest actions by small craft in the war. Half a year later the same Rizzo sank the Austro-Hungarian dreadnought Szent István in the Adriatic.