Captain John Bell was hailed a hero when he faced down the might of a German U-boat by ramming it with his tiny, unarmed cargo ship, becoming the first to sink such a vessel.
But like the U-boat Captain Bell’s story sunk into obscurity - until now, almost 100 years after the event, when his medals are to go for auction.
He went on the offensive after the fearsome submarine fired a torpedo at his small steamship in the English Channel.
He steered full steam ahead towards the U-boat's periscope until he and his crew heard a loud crash from beneath them.
Minutes later oil from the stricken sub floated to the surface of the sea and it was never seen again.
Although just a few months into the First World War, German U-boats posed a real menace to Royal Navy shipping, with five cruisers being lost to them in the first 10 weeks.
After returning to port news that Capt Bell's ship had become the first to sink one got out and he and his crew were given a reward of £860, the equivalent of £75,000 today.
He also received the Distinguished Service Order by King George V at Buckingham Palace, an 18 carat gold watch and given a celebratory dinner at the Mansion House in London.
Now 98 years later, his DSC and engraved watch are being sold at auction in London with a pre-sale estimate of £5,000 pounds.
Capt Bell's ship, the SS Thordis, had been travelling from Newcastle to Plymouth with a cargo of coal when it came under attack eight miles off Beachy Head, East Sussex, in February 1915.
In his deposition later made to customs officers at Weymouth, Dorset, Capt Bell said: "I observed periscope of submarine on starboard bow.
"I immediately ordered all hands on deck in case of emergency. I then observed submarine pass across our bow and on to our port beam, where it took up a position 30 to 40 yards off.
"Shortly after this I noticed the wake of torpedo on my starboard beam. I then put my helm hard over to starboard and ran over periscope, when I and all the crew heard and felt crash under bottom.
"I did not see submarine after, but saw oil floating on water. I then proceeded on voyage."
Capt Bell was mentioned in despatches a month later. The write-up in the London Gazette read: "Lieutenant John William Bell, Royal Naval Reserve, of the steamship 'Thordis' for his gallant and spirited conduct in ramming a German submarine, which had fired a torpedo at the 'Thordis'."
The gold stopwatch being sold is engraved with the words '...for sinking the first German submarine in the great European War 1914-15."
James Morten, of auctioneers Morten and Eden, said: "John Bell was a merchant seamen, he wasn't a military person.
"Yet when attacked by a menacing U-boat his instincts weren't to turn and run but quite the opposite.
"After spotting the periscope he decided to ram the submarine and all the evidence was that he sunk it.
"He was feted as a hero and trumpeted for being the first person to sink a German submarine of the war."
The auction takes place in London on July 2.
