HMS Sickle was a third-batch S-class submarine built for the Royal Navy during World War II.

From 10 May to 10 October, the boat patrolled the Gulf of Genoa five times and sank a German submarine as well as three minesweepers and an escort ship.

She then moved to Beirut, French Lebanon, and conducted two patrols in the Aegean Sea, sinking three caïques and a merchant ship, in addition to landing resistance operatives in Greece.

Several months later, the boat returned to service and conducted two patrols in the Aegean, sinking another three caïques, a sailing vessel, and a merchant ship.

[6] On 28 November 1942, the boat, under the command of Lieutenant James Drummond, sailed to Holy Loch, where she was commissioned into the Royal Navy three days later.

Sickle then sailed from Great Britain to Gibraltar on 6 April, with orders to intercept the Italian blockade runner Himalaya which was thought to be in the vicinity.

[11] The next day, Sickle attacked the German submarine U-303 off Toulon and hit it with two torpedoes; U-303 sank in half a minute.

In the evening of 28 September, the submarine landed two men near Sestri Levante, Italy; their mission was to gather intelligence as well as organize resistance movements and escapes of Allied prisoners of war to Switzerland.

On 30 September and 3 October, Sickle attacked a small coastal trading vessel and a submarine chaser with three torpedoes each, missing with all six.

The next day, her periscope was sighted while looking into the harbour at Karlovasi, and she was attacked with depth charges by the German torpedo boats TA14 and TA15; Sickle sustained significant damage, especially to her electric motors.

On 23 December, the submarine landed four Special Operations Executive Greek resistance men in Kalomos Bay, east of Euboea.

Three days later, she sank with gunfire and by ramming two small unidentified Greek sailing vessels east of Mykonos Island; the crews of both ships were picked up by Sickle.

The next day, the boat sank three Greek sailing vessels with demolition charges and by ramming in the Doro Channel.

She initially attacked them on the surface with her deck gun, but it jammed after firing four rounds, so Sickle boarded the first ship, a caïque flying the Greek flag with the German occupation pennon.

The ship was carrying a cargo of oranges and lemons, and sailors from Sickle brought a thousand of these to their submarine as an addition to their diet, then holed the caïque's hull, sinking it.

On 4 June, she engaged enemy ships on the surface at Mytilene; two sailors were wounded, one killed, and another washed overboard and captured.

A submarine, again possibly Sickle, sank the caïque Efitichia with gunfire and bombarded a shipyard at Mytilene on 14 June 1944.

[7][15][16] During her service with the Royal Navy, Sickle sank 10 Axis ships for a total of 7,665 GRT as well as a German U-boat, three caïques and a sailing vessel of unknown tonnage.