In October 1918, when it was becoming clear that the Central Powers would not prevail in the war, and that their navies would become subject to confiscation by the Allies, Emperor Karl I of Austria decided to turn over Viribus Unitis to the newly created Council of Slovenes, Croats, and Serbs that would soon occupy formerly Austrian territories on the Adriatic. Italy, however, had designs on some of the Austrian territory that might be turned over to the Croats, and didn't like the idea of 3 modern dreadnoughts being in the possession of the Austrian successor state. Although the SCS declared that it was no longer at war with the Allies, this declaration was not immediately recognized on the Allied Accordingly, Italy dispatched a pair of young men named Raffaele- one a Lieutenant Paolucci, and the other a Major Rossetti- to infiltrate Pula Harbor on a modified torpedo and attach a bomb to the dreadnought's hull. This the Raffaeles succeeded in doing, but they were captured while escaping, and brought on board the Viribus Unitis.
When the Raffaeles were brought on board, they told Admiral Vuckovich (the new commander of the dreadnought) that they had affixed a bomb to the hull and that the ship should be evacuated. This put the admiral in an awkward position. He could evacuate, but that would ensure the loss of the battleship when the mine exploded. The Viribus Unitis class was notorious for its poor underwater protection, making the threat of the bomb particularly potent. While it could be argued that the admiral should have evacuated VU anyway, thus saving the lives of his men, the ship was an extraordinarily expensive piece of state property. The men onboard the ship expected that they might have to die or kill in its defense. It was reasonable at the time to believe that the ship might be used to fight or deter the Italians. As such, evacuation doesn't present a very compelling option. Instead, the admiral decided to keep enough sailors on board to allow the best possible response to the damage that the bomb would cause. Inevitably, it risked the deaths of many sailors, but at the same time held out the best chance for saving the ship.
But what of the Raffaeles? The Italian officers had already admitted that a bomb was attached to the hull, and that it would explode in a relatively short period of time. They begged Admiral Vuckovich to be allowed to escape, and he agreed to let them go. However, when they reached the water they were assailed by angry sailors, and then dragged back onto the ship. Fearing prosecution (and potentially execution) for what amounted to a legally questionable attack on what its owners presumed to be a neutral vessel, the Italians demanded to be treated as prisoners of war. Admiral Vuckovich made no determination at the time, but ordered the crew not to harm the Italians. Twenty-five minutes later the bomb exploded. Fifteen minutes after that Viribus Unitis rolled over and sank with 300 men, including Admiral Vuckovich but not including the Raffaeles, who were allowed by Admiral Vuckovich to escape, and who spent about a week as prisoners of war.