HMS Unique was a British U class submarine, of the second group of that class, built by Vickers Armstrong, Barrow-in-Furness. She was laid down on 30 October 1939 and was commissioned on 27 September 1940.
She spent most of her career operating in the Mediterranean from mid 1941 under the command of Captain Arthur Hezlet, where she sank the Italian passenger/cargo ship Fenicia and the Italian troop transport Esperia. She also damaged the Italian cargo ship Arsia, which was later declared a total loss. On 5 January 1942, she made an unsuccessful attack on the Italian battleship Littorio.
Unique left Holy Loch after a refit, for a patrol in the Bay of Biscay on 7 October 1942. She left her escort off the Scillies on the 9th. No more was seen or heard from her after that date. HMS Ursula was in the area on the 10th and reported hearing underwater explosions that led her to believe Unique was under attack although the Germans made no claims to her sinking. She was reported overdue on 24 October 1942 when she failed to arrive at Gibraltar.
Three ships of the Royal Navy have borne the name HMS Unique:
HMS Unique was the French 12-gun schooner Harmonie that Cyane captured from the French in 1804. A French privateer recaptured and sank Unique in 1806.
On 27 January Cyane captured Harmonie at Lat. 15 Deg. 23 Min. North, Long. 60 Deg. 30 Min. West. Captain Joseph Nourse of Cyane reported that Harmonie was armed with 12 guns and had a crew of 82 men. She was 34 days out of Guadeloupe and had taken one prize, the Scottish ship Mercury, which was carrying a cargo of lumber and provisions to Demerara via New York. However, Hippomenes had recaptured Mercury on 26 January.
The Royal Navy took Harmonie into service as HMS Unique. Lieutenant James Baird commissioned her at Barbados for the Leeward Islands. Lieutenant George Rowley Brand replaced Baird within the year.
Unique formed part of Commodore Samuel Hood's squadron at the capture of Surinam River in 1804. The squadron consisted of Hood's flagship Centaur, Pandour, Serapis, Alligator, Hippomenes, Drake, and transports carrying 2000 troops under Brigadier-General Sir Charles Green. Lieutenant Brand went on shore, as did a number of other naval personnel, to participate in the attack. British and Dutch casualties were light, but Brand was severely wounded in the attack on the Dutch shore battery at Fredericki.