Sinking of Viribus Unitis

At dawn on 1 November 1918, in the naval harbour of Pola, the dreadnought Viribus Unitis, until recently the flagship of the Austro-Hungarian fleet, blew up and sank within some fifteen minutes. The mine under her hull was laid by two officers of the Italian Regia Marina, Major of Naval Engineers Raffaele Rossetti and Surgeon Lieutenant Raffaele Paolucci, who had got into the harbour during the night on the Mignatta human torpedo (PL). They did not know that the day before Emperor Charles had handed the fleet over to the National Council in Zagreb, and that the flag of the new State of Slovenes, Croats and Serbs was already flying over the battleship. The newly appointed commander of the new state’s fleet, Rear Admiral Janko Vuković de Podkapelski, was killed, together with several hundred sailors.

Mignatta

Pola was the most important base of the Austro-Hungarian Navy, and throughout the war the Italians had failed to attack the ships lying there effectively, although they had tried several times. The dreadnoughts lay in a harbour protected by booms and nets, and rarely came out to fight. Rossetti, an engineer from the arsenal at La Spezia, built a craft in 1918 that was meant to overcome these obstacles. It was a converted torpedo with electric propulsion, on which two men rode with their heads above water, carrying two explosive charges of roughly 170–200 kilograms each with time fuzes. The charge was attached to the hull of a ship. Paolucci, a naval doctor and an experienced swimmer, volunteered for the operation. The two trained for a long time, and as the war was drawing to a close, the attack was brought forward to the night of 31 October – 1 November.

On the afternoon of 31 October two torpedo boats and two MAS motor torpedo boats left Venice under the overall command of Commander Costanzo Ciano. Near the Brijuni Islands the boat MAS 95 towed the Mignatta close to the Pola breakwater, and at about 10 p.m. Rossetti and Paolucci went on alone. For several hours they hauled the craft across one barrier after another, unnoticed by the sentries and patrol boats. According to their account, at about 3 a.m. they got in among the anchored ships, and only before 5 a.m. did they reach the side of Viribus Unitis. Rossetti fixed the charge to the hull and set the fuze for 6.30 a.m. Moments later the two were spotted and fished out of the water. Before they were captured, Paolucci armed the second charge, and the abandoned craft drifted towards the ship Wien, lying a few hundred metres away, which had until recently served the Germans as a floating barracks.

The explosion

The prisoners were brought aboard Viribus Unitis. To their astonishment they saw that the sailors wore Yugoslav badges on their caps and treated them without hostility. They learned that the ship no longer belonged to Austria-Hungary. Then, shortly before 6 a.m., they told Vuković that the battleship could blow up at any moment, although they did not reveal where the charge was. Accounts of what happened next differ in detail. Vuković ordered part of the crew to leave the ship, and according to most descriptions the prisoners were sent to her sister ship Tegetthoff. When nothing happened at 6.30, the sailors began to return on board, taking the warning for a trick. At about 6.44 the charge exploded. Viribus Unitis listed, capsized and sank in roughly a quarter of an hour. The explosion of the second charge also sank the Wien.

Vuković died in the water. According to Italian accounts he was struck by a falling part of the ship while trying to swim to safety. The number of victims is not known. The British author Henry Baerlein wrote in 1922 of about 50 dead, a statement by the Croatian Ministry of Defence in 2014 speaks of about 250, and many accounts give 300–400 dead and missing. The exact number cannot be established also because, after the handover of the fleet, some of the non-Slav sailors had gone home, and chaos reigned on the ships: since the end of October they had been run by sailors’ councils.

After the sinking

The Italians did not recognise the handover of the fleet to the National Council and continued to treat the ships at Pola as Austro-Hungarian. Two days later the Armistice of Villa Giusti was signed, which required the fleet to be handed over to the victors regardless of the flag it was flying. Rossetti and Paolucci regained their freedom a few days later, when the Italian navy entered Pola. Both received the Gold Medal of Military Valour. The reward of 1.3 million lire for sinking Viribus Unitis, set back in the spring, went after disputes with the naval command to the two of them alone, and according to the Italian naval historian Rastelli they gave it to Vuković’s widow for the education of her son. The Mignatta became the prototype of the Italian human torpedoes of the Second World War.