Under Master William Waldie, Thurso was part of Convoy HG 84[1] which had left Lisbon for Liverpool, and called at Gibraltar on 9 June to join with the 36th Escort Group under the command of Captain "Johnnie" Walker.

It was a fine night, with good visibility; the wind was south easterly, force 2 and there was a slight swell after things had quietened down.

[2]Thurso carried 850 tons of cork, general cargo, and 1,500 bags of mail for German prisoners of war in Britain.

[2]At 00.58 and 00.59 hours on 15 June 1942 the U-552, commanded by Kapitänleutnant Erich Topp attacked convoy HG84[3] sinking three ships, the Etrib,[4] Pelayo[5] and Slemdal.

We had received no warning of submarines being in the vicinity and consequently did not know that danger was imminent until 0100 on June 15th when the 2nd officer reported that the Norwegian tanker Slemdal,[6][3] which was in position 62, had been torpedoed on the starboard side.

At 0600 the ship finally sank by the stern & at 0620 the survivors, including the two injured gunners were picked up by HMS Marigold & the casualties were immediately given medical attention.

The gun layer Hagon, who was suffering from internal injuries, managed to crawl unaided along to the boat-deck and into a boat, where he collapsed.

[10] The master, Captain Waldie, 22 crew members and the six gunners survived to be picked up by the corvette HMS Marigold and were landed at Greenock.

I remember so often thinking that those in the engine rooms, if they were torpedoed, would probably be drowned before they reached the engine room steps[12] Historian John Keegan wrote: The 30,000 men of the British Merchant Navy who fell victim to the U-boats between 1939 and 1945, the majority drowned or killed by exposure on the cruel North Atlantic sea, were quite as certainly front-line warriors as the guardsmen and fighter pilots to whom they ferried the necessities of combat.