French submarine Perle (1935)

Perle was a Saphir-class submarine built for the French Navy in the mid-1930s. Laid down in 1931, she was launched in July 1935 and commissioned in March 1937. In November 1942, after Operation Torch, Perle joined the Allied fleet. While returning from refitting in the United States, Perle was mistaken for a U-boat by an aircraft from the British Merchant Aircraft Carrier Empire MacCallum and sunk.

Design
Perle had a surfaced displacement of 761 LT and a submerged displacement of 925 LT. She was 66 m long, with a beam of 7.1 m and a draught of 4.3 m. Propulsion while surfaced was provided by two Normand-Vickers diesel engines with a total of 1300 bhp and while submerged by two electric motors providing a total of 1000 hp through two shafts giving a maximum speed of 12 kn while surfaced and 9 kn while submerged. Her bunkers of 95 LT of diesel fuel gave her a surfaced range of 7000 nmi at 7.5 kn and 4000 nmi at 12 kn, and her batteries gave her a submerged range of 80 nmi at 4 kn. She carried a complement of 42 men and could dive to a depth of up to 80 m.

The Saphir-class submarines were armed with torpedoes and could lay mines without surfacing. The moored contact mines they used contained 220 kg of TNT and could be laid in waters up to 200 m deep. They were attached to the submarine's exterior under a protective hydrodynamic housing.

Service history
Laid down in 1931, Perle was launched in July 1935 and commissioned in March 1937. In November 1942, after Operation Torch, Perle joined the Allied fleet and was assigned to Dakar. After taking part in several operations, Perle sailed to the United States for refitting. On 26 June 1944, it left port and, after stopping in Newfoundland, Perle set sail for the port of Dundee in Scotland to participate in operations off Norway. On 8 July, Perle was mistaken for a U-boat by an Allied Fairey Swordfish and sunk in position 55.45°N, -30.83333°W. Approximately 17 of the crew of 42 survived the sinking but only one was rescued. The crew killed aboard Perle were the last casualties among French submariners in World War II.