HMS Sceptre (P215) was a third-batch S-class submarine built for the Royal Navy during World War II.

The operation, codenamed Guidance, encountered difficulties with the attacking submarine's charts, and the explosives were laid on a merchant ship close to the dock instead.

Sceptre then conducted a patrol in the Bay of Biscay, sinking two German merchant ships, before being reassigned to tow X24 to Bergen again.

After a last patrol in which she sank one ship, Sceptre underwent a lengthy refit to serve as a high-speed target submarine for training purposes.

[6] On 15 April 1943, Sceptre, under the command of Lieutenant Ian McIntosh, sailed to Holy Loch, where she was commissioned later in the day.

[8] After going through training exercises off Scapa Flow and Holy Loch, Sceptre set sail on 20 July 1943 for an anti-submarine patrol off Norway.

On 12 September 1943, the boat departed port towing the X-class submarine X10 to her target, the German battleship Scharnhorst.

On 20 September, the midget submarine was released to attack the battleship Tirpitz, but experienced engine troubles and had to abandon the mission.

On 12 and 13 March, the submarine fired torpedoes at the merchants Kong Harald and Gordias, but failed on both occasions to score a hit.

X24 successfully entered the harbour two days later, but faulty intelligence and incorrect charts resulted in the explosive charges being laid on the German merchant Barenfels and not on the dock.

[11] The ship was sunk and the dock damaged, and X24 rendezvoused with Sceptre and both submarines left the area at full speed; only later was X24 taken under tow again.

[7] After training for operations with X-class midget submarines at Port HZZ, the boat departed on 7 September, towing X24 to her target, the same floating dry dock in Bergen.

Sceptre released X24 in the evening of 10 September; X24 penetrated the harbour in broad daylight, avoiding tugs and ships, and successfully placed her explosive charges under the targeted dock.

[7] During her service with the Royal Navy, Sceptre sank five ships for a total of 15,084 gross register tons (GRT).