Italy:
Battleship
Dante Alighieri moored in the harbour of Fiume, between 1919 and 1920
The "
Impresa di Fiume", in which Italian writer and political activist Gabriele D'Annunzio led veterans and sympathizing soldiers to occupy the city of Fiume, had interesting repercussions for the Regia Marina, that had deployed quite a number of ships in the area (also in Istria and Dalmatia, to support Italian interests there, matter that had always been important to it), as the occupation received wide support within the armed forces, including the crews of several ships.
While the Regia Marina ordered the ship to get out when the city was occupied, only the elderly battleship
Emanuele Filiberto and the destroyer
Francesco Stocco were able to; due to the effort of D'Annunzio's "
legionari", the crew of the battleship
Dante Alighieri split and it could not sail, thus it was authorized to remain there, functioning somewhat as "representative" of the legitimate government. Contrammiraglio Franco Nunes, highest-ranking Italian naval officer, accordingly raised its flag on it. Throughout the occupation several ships (mainly destroyers and torpedo-boats) effectively deserted, and others attempted to, to join the legionnaire cause, forming a small navy.
In December 1920, when it was decided to deal with D'Annunzio's matter with force, the Regia Marina again ordered the ships under its command in the harbour to leave; the
Dante was unable to, however, as the legionnaires towed a merchantmen across the entrance, blocking it in. Therefore, on 26 December, when the RM (led by the battleship
Andrea Doria) did its part in the repression of the rebels (what is called in Italy the "bloody Christmas"), the
Dante was a spectator, although, unlike on land, there were no clashes between the government's ships and those that had joined D'Annunzio.
Interestingly enough, the ships that had deserted and were later retaken by the Regia Marina were all rechristened, as if to cancel the fact from memory. The several officers and men were duly tried, but were given mild sentences, ostensibly because their actions had been motivated by "patriotism".
Overall, the Impresa di Fiume constituted the biggest instance of either disobedience or outright mutiny within the Italian Navy, in its history.