When the armistice between Italy and the Allied forces was announced, on the evening of 8 September 1943, the harbour of Bastia, in Italian-occupied Corsica, was packed with both Italian and German vessels; moored in the harbour were the Italian Ardito and Aliseo, the Italian merchant shipsSassari and Humanitas, and a small German flotilla which included the submarine chasersUJ 2203 and UJ 2219 and five Marinefährprahme. The Cormorano was on watch off Bastia. The local Italian and German commanders soon reached a "gentlemen’s agreement" according to which the German forces would be allowed to safely retreat to mainland Italy. Meanwhile, however, the German forces secretly prepared to launch a surprise attack on the Italian ships moored inside the harbour, planning to capture them. The attack started at 23:45 on 8 September, when two groups of German soldiers, after hearing a whistle, stormed Ardito; the torpedo boat was heavily damaged and captured, and the merchant ships Sassari and Humanitas also fell into German hands. On board Humanitas, German gunners manning the anti-aircraft guns turned their weapons on the Italian crew and soldiers aboard, and the Italian lookouts were stabbed or killed with hand grenades.
Action
Aliseo had just left the harbour when the German attack began. Shortly after dawn on 9 September, a combat group of the Tenth Bersaglieri Group staged a counterattack which led to the recapture of the port. Ardito, Sassari and Humanitas were also recaptured. The German flotilla was ordered to leave the harbour, but as soon as they left, the ships were shelled by the Italian coastal batteries, which damaged UJ 2203 and some of the MFPs. Aliseo was then ordered by the port commander to attack and destroy the German units. Shortly after 7:00 the flotilla, proceeding in a column led by UJ 2203, opened fire on Aliseo, which returned fire at 7:06, from a distance of ; at 7:30 Aliseo was hit by an 88 mm shell in the engine room and temporarily left dead in the water, but the damage was quickly repaired and the torpedo boat closed in and engaged her adversaries in succession, destroying them one after the other. At 8:20 UJ 2203, after suffering several hits, blew up; ten minutes later UJ 2219 was also destroyed when her magazines exploded. Between 8:30 and 8:35 Aliseo also sank F 366, F 459 and F 623; Cormorano intervened during the final phase of the battle and, together with Aliseo, forced F 387 and F 612 to run aground, after which they were abandoned and destroyed. Cormorano also sank the 43-ton Luftwaffe service motorboat FL B. 412. Twenty-five German survivors were picked up by Aliseo, which then proceeded towards Portoferraio, as ordered. The damage suffered by Ardito later caused this ship to be left behind in Portoferraio, where she was eventually captured by German forces.
