The Italian submarine Nichelio meets the Salerno invasion fleet after the surrender of Italy, on 9 September 1943. Note the small black pennant flying at the periscope, the recognition mark to show compliance with the armistice orders.
Photo source, Naval History and Heritage Command.
As a rather colorful background for this photo, here’s a excerpt from the book “Dark Navy: The Italian Regia Marina and the Armistice of 8 September 1943”, by Enrico Cernuschi and Vincent P. O’Hara, originally quoted by /u/phoenix_jz on /r/warshipporn:
In the hours after the armistice there had been many encounters between Italian and German forces, but the first meeting between Italian and Allied naval units did not occur until a few minutes past 0800 on 9 September when the Italian submarine Nichelio surfaced off Salerno in accordance with orders she had received the night before. Within minutes three Royal Navy motor launches accosted her.
One of the British boats motored alongside and her commander shouted “You are prisoners.” He then threw a bundled Union Jack up on the submarine’s sail and tried to explain with gestures that he expected the Italians to raise this flag above their own. The Italian captain ignored the pantomime, re-bundled the package and threw it back. Twice the flag went from motor launch to submarine and back again. Tensions grew and machine guns were manned on both sides. At the third toss the flag fell in the water, opened and sank as both sides silently watched. Then the Italian captain said he wanted to speak to the admiral in command. The British decided this was a good idea and escorted the submarine alongside Admiral Kent Hewitt’s flagship, USS Ancon. The Italian captain told his XO to scuttle the boat if he did not return after two hours and, strapping on a pistol to emphasize that he was no one’s prisoner, he boarded Ancon. The lieutenant’s fears proved baseless as Admiral Hewitt welcomed the Italian submariner and accepted his word that he would not undertake any unprovoked hostile acts. No Allied sailor boarded Nichelio, while the Italians were allowed to visit Ancon, including the submarine’s dog, which received cheers from the American sailors and, along with Nichelio’s crew, demonstrated an appreciation for American chow