THE CANADIAN PRESS/Lucas Timmons

At about 4 a.m. on Dec. 1, 1940, three torpedoes streamed through the frigid North Atlantic.

Two missed their target, the destroyer HMCS Saguenay.

The third fired from the Italian submarine Argo hit with such force it lifted the ship's bow and threw Able Seaman George Borgal of Halifax, just 19 and keeping night watch on the open bridge, up into the air.

Archival photo of HMCS Saguenay showing damage. THE CANADIAN PRESS/Darren Calabrese

"I went flying," he told author Blake Heathcote years later for the book "Testaments of Honour: Personal Histories of Canada's War Veterans."

"My left leg was numb when I got up and I felt the ship start to roll, back and forth, and I thought she was going to go," he said. "Our mast was broken and a fire broke out and our bow was gone."

The Saguenay lost 21 men that night but managed to steam about 450 kilometres — backwards — into port at Barrow-in-Furness, England, for repairs.

Archival photo of HMCS Saguenay showing damage from being hit by a torpedo. THE CANADIAN PRESS/Darren Calabrese

She was among the hundreds of vessels that braved every kind of weather, from hurricane-force storms to giant seas, as they faced the constant underwater threat of enemy submarines during the Battle of the Atlantic.

Canada played a crucial, largely unsung role in the fight to maintain shipping supply lines to Great Britain, the vital Allied stronghold against German forces advancing across Europe.

The Battle of the Atlantic was the longest and arguably most important campaign of the Second World War. It stretched from the Sept. 3, 1939, sinking of the British passenger liner Athenia off the coast of Ireland until the last German U-boats surrendered after Victory in Europe Day in May 1945.

The S.S. Athenia, in Montreal in 1932. THE CANADIAN PRESS/HO-Clifford M. Johnston / Library and Archives Canada

The United Kingdom relied on constant arrivals from North America of troops, food, fuel, steel, aluminum and everything else needed to power its war machine against the Nazis.

Air travel and transport was still limited, said Marc Milner, author of "Battle of the Atlantic" and director of the Gregg Centre for the Study of War and Society at University of New Brunswick.

"Britain is an arsenal of democracy but the stuff's got to get there by boat," he said in an interview. "The war cannot be won without winning the Battle of the Atlantic."

Keeping supply lines open to the United Kingdom laid the ground work for Normandy and other operations that ultimately sealed Allied victory, Milner said.

"The Battle of the Atlantic could not have been won without Canada's contribution," he added. "By the winter of 1942-43, fully half of all the escorts on the main routes between North America — New York and Halifax — and British ports are Canadian naval escorts."

A stamp commemorating the Battle of the Atlantic in the Second World War. THE CANADIAN PRESS/HO-Library and Archives Canada; Copyright: Canada Post Corporation

The convoy system in which warships guarded supply-loaded merchant ships from submarine attack was "the bedrock of Allied victory," Milner said.

Canadians were the quiet administrators, the air traffic controllers of the sea, who kept a complex operation going for much of the conflict.

"Canada was a major player in naval control of shipping and naval intelligence in the Battle of the Atlantic," Milner said. "We actually ran all of that stuff for all of North America until about the middle of 1942 when the Americans were finally up to speed and were able to take over their own section of the North Atlantic."

"We're the people who trained them," as the U.S. entered the war after Japan bombed Pearl Harbour on Dec. 7, 1941.

The Royal Canadian Air Force also made up about one-third of all aircraft and crew protecting the convoys from above, Milner said.

Battle of the Atlantic

Battle of the Atlantic timeline: From Sept. 3, 1939, when the British passenger liner Athenia is sunk off the coast of Ireland to 1945. It was the longest single campaign of the Second World War.

The S.S. Athenia, in Montreal in 1933. THE CANADIAN PRESS/HO-Clifford M. Johnston / Library and Archives Canada

During the 2,075 days of the Battle of the Atlantic, the Royal Canadian Navy escorted 25,343 merchant vessels carrying crucial supplies to Great Britain in often brutal weather and sea conditions, under constant threat of U-boat attack.

The Royal Canadian Navy Ensign

Royal Canadian Navy casualties: 1,990 dead, 319 wounded, 95 became prisoners of war; 33 warships lost, five damaged beyond repair. The RCN captured or destroyed 42 enemy surface ships and helped sink 33 enemy submarines.

A badge worn by members of the Canadian Merchant Navy

Merchant Navy: More than 1,700 dead (including Canadian seamen lost while serving on 278 Canadian and Allied ships); more than 70 Canadian merchant ships sunk.

Royal Canadian Air Force Ensign

Royal Canadian Air Force: More than 900 air crew killed and about 350 aircraft lost.

Royal Canadian Navy growth during the Second World War: From 10 modern warships and 3,276 personnel in 1939 to 400 warships and almost 100,000 personnel. The RCN was the world's fourth largest navy by 1945.

SOURCES: Royal Canadian Navy and National Defence

Former British prime minister Winston Churchill would later write that the Battle of the Atlantic was so pivotal that all other war efforts by land or air depended on its outcome.

"The only thing that ever really frightened me during the war was the U-boat peril," he wrote in "Their Finest Hour," part of his six-volume history of the Second World War.

Shipping losses reached a startling peak in 1942, raising alarms that Britain might not be able to import the yearly requirement of 25 to 30 million tonnes of food, raw materials, oil and other goods, Milner said.

Canadians stepped up as support staff to keep goods flowing at a time when the Royal Canadian Navy was still a comparatively fledgling force, he said.

"We did a lot with armed yachts and old trawlers and anything that would go.

"It allowed the British in particular to get really good at what they were doing, which was killing submarines."

The Royal Canadian Navy grew in that period from 10 modern warships and 3,276 personnel to 400 warships and almost 100,000 members. By 1945, it was the world's fourth largest navy.

Canada's surface navy at the end of the Second World War. THE CANADIAN PRESS/Lucas Timmons

It was one motley crew in the war's earliest stages, Milner said. Canadian corvette commanders were often former reservists or merchant seamen called to service — including a fair number of ex-liquor movers.

"And then there were people from the marine service of the RCMP who'd spent much of the '30s chasing them while they were running rum around the East Coast.

"You had this curious navy made up of characters on both sides of the law who were then out fighting Germans."

Milner hails those Merchant Navy sailors as true heroes who, despite high casualty rates, had to fight decades after the war for official recognition and veteran benefits.

He also specially mentions the corvette commanders and merchant vessel captains who worked relentless schedules under punishing stress. Many senior officers did not survive long after the war, he said.

They were men like Chummy Prentice, captain of the corvette HMCS Chambly who helped log the Royal Canadian Navy's first sinking of a U-boat in September 1941.

Prentice sported a monocle and didn't bat an eye when his whole crew turned up one day with their own eye pieces, Milner said.

"It's said that Prentice threw his head back, flipped the monocle in the air, caught it between his eyelid and his cheek and said: 'When you can do that, you can all wear monocles.'"

George Borgal, the son and namesake of that young watchman who survived the 1940 torpedo attack on the Saguenay, also marvels at the endurance of those crews.

George Borgal holds an archival photo of HMCS Saguenay in his home in Halifax on Tuesday, May 16, 2017 after the ship was rammed by a merchant ship. Borgal's father, Also named George Borgal, was a 19-year-old able seaman on watch the night HMCS Saguenay was hit by a torpedo in December 1940, but still managed to steam almost 450 kilometres, backwards, to port at Barrow-in-Furness, England. THE CANADIAN PRESS/Darren Calabrese

"He would have nightmares," he said of his father, who lived through other close calls at sea, including a ramming with another vessel and a hurricane.

"You have to admire the strength of character of people who go through that."

Archival photo of George Borgal who was a 19-year-old able seaman on watch the night HMCS Saguenay was hit in December 1940, but still managed to steam almost 450 kilometres, backwards, to port at Barrow-in-Furness, England. Pictured in Halifax on Tuesday, May 16, 2017. THE CANADIAN PRESS/Darren Calabrese

Borgal is now head of a working group with the Canadian Naval Memorial Trust aimed at building Battle of the Atlantic Place. It would be a new museum in Halifax showcasing HMCS Sackville — a surviving corvette — and Canada's role in the campaign.

"It was crucial to the success of land battles," Borgal said of the country's collective effort, ensuring more than 25,000 merchant vessels crossed the Atlantic under Royal Canadian Navy escort.

"Without the battle having been won, Normandy wouldn't have happened, the relief of Stalingrad wouldn't have happened and the course of our future would have looked very different."

Every year on the first Sunday of May, Canada's naval forces honour those lost at sea during the Second World War. They pause, pray and remember the legacy of the Battle of the Atlantic as they pledge themselves anew: "Ready, aye, ready."

Battle of the Atlantic

Norman Crewe still hears the sound of men crying out from the dark waves of the North Atlantic for help that wouldn't come in time.

"It stays with you for the rest of your life," he said. "You'd never forget it if you lived to be 100."

Crewe, who is 95 now, was among 12,000 men and women who served in Canada's Merchant Navy during the Battle of the Atlantic.

Norman Crewe, 95, who served with the Merchant Navy throughout the Battle of the Atlantic, poses in his home in Halifax on Thursday, May 4, 2017. THE CANADIAN PRESS/Darren Calabrese

The pivotal fight between the Allies and Germans for control of crucial shipping supply routes was the longest campaign of the Second World War. It stretched from September 1939 to when the last of the German U-boats surrendered after Victory in Europe Day in May 1945.

Crewe made at least 14 round trips on vessels bound for Britain carrying everything from eggs to ammunition. He travelled in columns of ships that stayed together for protection against attack from above and below. Enemy aircraft and submarines were constant threats.

If a ship two columns over got torpedoed, the others had to keep going, Crewe recalled.

"You were not allowed to stop."

Once the rest of the convoy passed, an escort would go back to circle for survivors, he said from his home in Halifax, where he first joined the Merchant Navy in 1940.

To this day, his heart goes out to those doomed men in the water.

"Not only did they drown but a ship coming up in the same column behind, in the dark ... they'd just run over those guys. They wouldn't know it."

Norman Crewe, 95, who served with the Merchant Navy throughout the Battle of the Atlantic, prepares his naval sash in front of his wife Millie in their home in Halifax on Thursday, May 4, 2017. THE CANADIAN PRESS/Darren Calabrese

Crewe resisted telling such stories for decades. But in recent years he has spoken in schools about memories that still fill his eyes and halt his speech.

"I realize now, if we don't tell the kids what really happened, how are they going to be able to tell somebody else about it?"

Crewe has two great grandsons who aren't yet in high school.

"I pray to God the day will never come that they will have to go through what we went through."

Crewe served mainly on the Lady Rodney, one of five vessels named for the wives of British admirals with ties to the West Indies. It was known before the war in the 1920s and '30s as a luxury cruise liner.

C.N.S. Lady Rodney in Montreal in 1930. THE CANADIAN PRESS/HO-Clifford M. Johnston / Library and Archives Canada

Crewe's experience was different. He remembers the time he was most frightened: arriving to board the vessel for a July 1943 trip from Halifax to a British naval base. The ship's exposed forward decks were chock full of depth charge anti-submarine explosives in full view of enemy planes.

He said by the time they reached their destination a week later, "I could recite the Lord's Prayer backwards."

"All we needed was just one to go, and of course it would be like a flash of lightning."

And then there were storms.

"Anybody that travelled the North Atlantic in the winter time, they went through hell and high water," Crewe said.

Many times the rails on his bunk kept him from pitching out of bed in vicious weather that turned waves into mountains. He and other young seamen, just kids in their early 20s, were often called out on decks to chip away thick ice that formed as spray froze.

Icebergs were a major hazard in spring.

"The worst was what we called growlers. Those are chunks of ice just above the water," that can slice a metal hull like a can opener, Crewe said. "Those are very, very dangerous."

He lost more friends than he can count or name. "Too many."

Norman Crewe, 95, who served with the Merchant Navy throughout the Battle of the Atlantic, reaches for the jacket of his uniform in his home in Halifax on Thursday, May 4, 2017. THE CANADIAN PRESS/Darren Calabrese

Canada's Merchant Navy had a staggering casualty rate, with more than 1,700 dead and more than 70 Canadian merchant ships sunk.

"I'm one of the lucky ones," Crewe said. "I came back."