In the summer of 1943, staff at Quebec City's Château Frontenac were only given a few weeks notice they'd soon be hosting British Prime Minister Winston Churchill and U.S. President Franklin D. Roosevelt.

The Second World War had been dragging on for nearly four years — and the Allies were to meet to discuss how to push back the Axis powers in Europe.

But despite the top-secret nature of the meetings, one young Quebec soldier walked out of the famed hotel with information that could have changed the outcome of the war.

In August 1943, without raising the slightest suspicion, Sgt. Maj. Émile Couture, from Thetford-Mines, Que., left work and walked past the security guards, who were familiar with the young soldier in charge of stationery supplies.

Couture, then 25, was instructed to clean up after meetings at the Quebec Citadelle and the Château Frontenac, and make sure nothing was left behind.

He was tidying an office on the third floor of the hotel when he found a leather portfolio with an inscription in gold: "Churchill-Roosevelt, Quebec Conference, 1943."

Several newspapers and military magazines published Couture’s story in the years following the Second World War, including this article published in June 1962 in the Legionary. (Submitted by Anne Couture)

Couture figured he'd "bring one home as a souvenir," he said in a 1972 interview with Radio-Canada's radio program Appelez-moi Lise.

"But I didn't know what was in it," he told host Lise Payette.

Couture left the Château Frontenac and drove to the cottage he shared with his cousins in Lac-Beauport, a few kilometres north of Quebec City.

It was only then that he discovered the portfolio contained detailed descriptions of Allied military assets — including the number of planes, combat cars, ships and ground soldiers on hand.

The portfolio also contained tactical plans for something code-named Operation Overlord, what would become better known as the D-Day invasion.

"That's when he got scared," said his daughter, Anne Couture, who grew up hearing his story.

The story of what Émile Couture did next will be on display in September at Quebec City's Royal 22e Régiment Museum, where it will be added to the permanent exhibit on the two Quebec Conferences that took place in the provincial capital during the Second World War.

Possible confinement

Anne Couture was just 17 when her father died in 1972. But she remembers that he always told the same version of what happened next.

Once the realization sank in that evening, Émile Couture hid the files under his mattress.

He drove to work the next morning and returned the portfolio to his superior, Brigadier Edmond Blais.

Couture was told "'Go home. Don't say a word. We'll deal with you in the morning,'" he recalled in the 1972 interview.

He was interrogated by Scotland Yard and the FBI.

Anne Couture said that as a low-ranking soldier, he "could have been imprisoned" until D-Day to ensure the information he had seen did not fall into enemy hands.

The Couture family still has the security passes Émile Couture was granted in 1943 and 1944, to access the Château Frontenac and the Citadelle. (Julia Page/CBC)

But Couture was instead sent home.

In a letter dated Aug. 28, 1943, the brigadier informed the Department of National Defence that Couture should be awarded "the greatest accomplishment that can be given an NCO."

Ten months later 150,000 soldiers landed on Normandy's beaches and pushed back the German troops. It was a pivotal moment that helped turn the tide of the war.

Couture, who knew about the invasion before most, had not breathed a word to anyone.

Awarded for good service

Hosted by Canadian Prime Minister William L. Mackenzie King, the seven-day conference in Quebec laid the groundwork for the Normandy invasion, as well as military strikes in Japan and Italy.

At a ceremony in September 1944 during the 2nd Quebec Conference, Couture was commended for his silence with a British Empire Medal.

But there was never any official mention of what he did to earn the medal beyond recognition for "services rendered."

Winston Churchill, Franklin D. Roosevelt and William L. Mackenzie King speak with reporters during a news conference at the Quebec Citadelle on August 18, 1943. (Submitted by Musée Royal 22e Régiment)

The loss of confidential military documents was not something officials wanted to see included in the public record, Anne Couture said: "How could someone have been able to leave the Château Frontenac with such crucial documents?"

While she insists her father kept quiet, the secret did eventually get out.

During the 2nd conference, the story was leaked to the press by another military member, according to Anne Couture.

This led to coverage in several international media outlets, including Newsweek and Time Magazine.

While he gave several interviews over the years, Émile Couture never revealed whose office he was cleaning, and who could have left such important files behind.

"Except, perhaps, to my mother," Anne Couture said.

'Piece of history'

Over the years, others have come forward claiming a family member of theirs was behind the discovery.

But Couture's widow, Georgette Larochelle, now 88, hoped to set the record straight, Anne Couture explained.

"It's important for us — for my mother and my family — that my father's story be known," she said.

Items the Couture family had been holding onto from the Quebec Conference will be displayed at Quebec City's Royal 22e Régiment Museum in September. (Julia Page/CBC)

Their collection has been handed over to the Royal Museum's director and curator, Dany Hamel.

The abundance of information leaves little place for interpretation, said Hamel.

"All the documents brought forward by the family are really convincing."

Several items will be displayed in the upcoming exhibit commemorating the 75th anniversary of the 2nd Quebec Conference, as of September 12.

Certain items, such as an ink blotter inscribed with Winston Churchill's name, are invaluable to the museum, Hamel said.

"They are personal belongings made especially for the conference, and are a great witness of this event of national significance."

Anne Couture and museum director Dany Hamel look at a magazine from 1944 that recounts Émile Couture’s story. (Julia Page/CBC)

For Anne Couture, being able to see her father's story being entered into Canadian history will be a moving experience, one she hopes to share with her grandchildren.

"If he hadn't kept the secret, who knows what would have happened."