Saturday marks the 70th anniversary of a short, violent battle off the coast of Wales involving three Canadian warships and U-1302 — an action that earned Simpson the Distinguished Service Medal.
At 93, Simpson is one of the few left alive of the 114 Canadians awarded that medal.
It was his determination and refusal to be brushed off by an inexperienced officer that led the frigate HMCS Hulloise and two other warships to attack the submarine, which was near the surface and tucked close to a buoy to avoid detection.
Simpson spotted the U-boat's snorkel on his radar, but the officer on watch dismissed his report. Simpson persisted and the frigate's captain decided to check out the contact.
The submarine was sunk with all 48 men aboard. Simpson says he has often thought about how swift and possibly how painful the end was for the German sailors who went to their watery grave beneath the pounding of the flotilla's depth charges.
"At first I was dumbfounded," he said in an interview from his home in Windsor, Ont. "It is one thing to take a person's life, but to take 30-40 men at one crack? I've had thoughts about it.
"I wondered how in the hell did they die? Did they have some kind of pill they would take in the kind of a situation where they knew they weren't going to survive? Did they drown?"
The battle was fought at night on a calm sea in St. George's Channel, one of the main convoy routes that funnelled much-needed supplies into Britain during the war.
According to naval archives and research conducted by Simpson's grandson, U-1302, a new boat, was on its first war patrol and had already claimed three merchant ships by the time the Canadian flotilla found it.
Simpson was on duty at 3 a.m. when his radar set picked up two "pips" close to the Welsh coast. He notified the officer of the watch who told him one of contacts must have been a marker buoy and ignored the other reading.
"He said, 'You must seeing gremlins,'" Simpson recalled. "And I said: 'Gremlins my ass' and I tore out of the shack. I was so mad I wanted to throw him overboard."
The captain heard the commotion and asked what was going on. When they explained, the skipper ordered the ship to steer for the contact.
As they closed within 1,000 metres and the searchlight came on, the crew spotted a submarine snorkel at the surface as the vessel recharged its batteries. The U-boat dove and the three Canadian warships pounced.
"It didn't take more than two or three runs of the other vessels to pin her down on the bottom and when the flotsam started to come to the surface, we knew she wasn't able to move," said Simpson.
"I often wondered, had I not been so blatant in my telling the officer to go and pound salt because he didn't know what the hell he was saying, what would have happened."
Simpson was recognized for his grit a year after the war when he was presented with the Distinguished Service Medal at a ceremony in his southern Ontario hometown.
And while he said he recognizes it was war and sinking the submarine saved lives, the action weighed on his conscience.
"It bothered me. Yes, it did bother me, but not so much anymore," he said. "I've let it be what it is."