The history of the Italian submarine Cappellini during the Second World War is undoubtedly unique and very special. It is distinguished by the fact that during the same war this submarine was used by three different nations: Italy, Germany and finally Imperial Japan.

The Cappellini was built by the Regia Marina Italiana in 1939 and was initially used for operations in the Atlantic, working alongside the German allies to attack and sink allied convoys from Canada and the United States. However, the submarine's history proved troubled from the very beginning of its military operations. On its first mission, it was almost immediately attacked by an American anti-submarine ship off the Spanish coast and was forced to quickly fall back into Spanish waters, lest it be destroyed. Later, after a return to Italy for repairs, the famous commander Salvatore Todaro was appointed to command it. He was a naval ace who became famous for an episode in which, after sinking a Belgian ship off the Azores islands, he decided to save its crew by throwing himself into the sea.

After the armistice of 8 September 1943, Italy surrendered to the Allies and the Cappellini was seized by the Germans, who incorporated it into their fleet of submarines, making it operate in the Pacific alongside the Japanese forces. When Nazi Germany surrendered to the Allies in 1945, the Cappellini was eventually seized again by the Japanese who prepared to modify it for use in the defence of their islands against American forces. However, before it could be used by the imperial navy, the Americans won the war by dropping atomic bombs on Hiroshima and Nagasaki.

The submarine's end came in the Pacific Ocean when, after being captured by the Americans, it was subjected to a controlled demolition operation. This famous submarine remains the only Italian World War II submarine to have been used by three different nations.