Antiope was a Diane-class submarine of the French Navy, authorised under the 1927 naval programme and laid down at Chantiers Worms le Trait in Rouen on 28 December 1928. She was launched on 18 August 1930 and commissioned in 1933 - one of the small, capable ocean-going boats that France was building to defend a long imperial coastline. She entered the Second World War on the Allied side. After the fall of France in June 1940, the boats and crews that found themselves in Vichy-controlled ports had to choose: fight on with the British, sit out the war under the new regime in southern France and its colonies, or be interned. The decision was complicated by Mers-el-Kebir and by oaths of obedience; Antiope ended up in the Vichy column.

On 25 May 1940, before the political earthquake, Antiope was part of a French flotilla that arrived in Dundee, Scotland - the tender Jules Verne and the submarines of the 2nd, 13th, and 16th Submarine Divisions. The boat's career then disappears for a stretch into the Vichy years; what reappears in the records is one of those small details that survive only because someone bothered to write them down. In 1942 her crew had managed, through a number of difficulties, to load a camel aboard. She was carrying the animal somewhere - exactly where is unclear - when she was diverted to escort the auxiliary cruiser and the French merchant ship Gabon, which was carrying an important cargo. The crew had to rush to put the camel ashore at Port-Etienne, in present-day Mauritania, before she could get back underway on 18 September 1942. The boat's commanding officer was, by the official account, visibly disappointed.

On 1 November 1942 Antiope was based at Casablanca with the 16th Submarine Division - Amazone, Amphitrite, Sibylle and the boat - when the French naval commander received word that an Allied invasion of French North Africa was imminent. Operation Torch began in the predawn hours of 8 November. Antiope cleared Casablanca at 06:30 bound for a patrol area in the Atlantic on a bearing of 165 to 200 degrees from El Hank. At 09:54, with the Naval Battle of Casablanca already raging - American battleships and cruisers were trading salvoes with French shore batteries and the cruiser Primauguet - Antiope fired six torpedoes at a US heavy cruiser. The torpedoes missed. A US submarine fired at her in return and also missed. Three US Navy F4F Wildcat fighters bombed her without effect. Antiope evaded everything and slipped back to Casablanca to refuel.

On 9 November Antiope and Amazone got underway from Casablanca for Port-Etienne. While they were at sea, the fighting between Allied and Vichy French forces in North Africa ended on 11 November 1942. The two submarines reached Port-Etienne on 15 November, spent the night, and proceeded to Dakar on 18 November. The French forces in Africa joined the Free French Naval Forces and Antiope, three days after firing torpedoes at the United States Navy, became a Free French boat. By 1943 she was integrated into a squadron of British submarines operating out of Algiers. On 27 April she ran a patrol off the Italian Riviera - found no targets, fired a torpedo at the piles of an Italian bridge, watched it bounce harmlessly off the riprap at the pile's base, and went home. A patrol off Corsica in July 1943 was similarly quiet. The wars of choice she had been built for were not the war she was now fighting.

On 28 March 1944 Antiope crossed the Atlantic from Gibraltar in company with a Polish submarine, a fleet tender, and a British naval trawler. She was assigned to the US Navy sound school at Key West, Florida, where Allied surface ships learned to find boats like her on sonar - practice targets for the men hunting the U-boats that were still sinking ships in the Caribbean. She moved on 28 December to the Philadelphia Navy Yard at League Island for a refit, returned to Key West on 26 March 1945, and was still there when the war in Europe ended on 8 May 1945. She left on 12 July, called at Bermuda and then Ponta Delgada in the Azores, and headed for Oran. The French Navy struck her from the list and condemned her on 26 April 1946. She had begun as a French boat, become a Vichy boat, become a Free French boat, become an Allied training boat, and ended as a write-off in an Algerian harbour.