"To the living we owe respect, but to the dead we owe only the truth," Johnston said, citing the words of the 18th-century French philosopher.
The truth is always a scarce commodity in war, regardless of when it's fought. The more distant the conflict, the more that's forgotten and given over to the mists of time — or the warping of popular culture.
A recent Veterans Affairs Canada survey found some three-quarters of respondents felt they were knowledgeable about the country's military history, but scholars have recently been asking: what do they know, let alone understand?
So much of Canada's collective memory is shaped by U.S. and British films, TV and now the unrelenting, often unreliable flash-bang of social media.
Say D-Day and many members of the iPod and Twitter generation might think first of "Saving Private Ryan," the 1998 blockbuster starring Tom Hanks, before they do the epic battle of June 6, 1944.
Hollywood's retelling of D-Day often doesn't even include Canada. As far as popular culture is concerned, it was U.S. and British soldiers who charged up the beaches into the teeth of German machine guns and shelling.
Terry Copp, historian, author and director of the Laurier Centre for Military and Strategic Disarmament Studies, looked at Canadian attitudes on D-Day for an essay and was surprised by what he found.
"Canadians began to get interested in D-Day over the fuss on the movie The Longest Day (1962), which didn't mention Canadians and then they got interested again with Saving Private Ryan (1998), which didn't mention Canadians," he said.
In some respects, it has long been that way. Witness the 1963 Steve McQueen film "The Great Escape," which recounted the massive March 1944 break-out from the German prisoner-of-war camp Stalag Luft III.
The fact that Canadian airmen played an indispensable role in planning and executing that escape was scrubbed out of the script — and popular memory.
Author and military historian Ted Barris set out to set the record straight last year with his book "The Great Escape: A Canadian Story," published to critical acclaim.
Last August, he was one of the keynote speakers at a reunion of U.S. Stalag Luft III POWs, their families and descendants.
"Are there any Canadians in the audience because I might need their protection getting out of here alive," Barris said, recalling how he began the speech.
He proceeded to methodically correct aspects of the film — fabrications for dramatic purposes, truths deliberately distorted to appeal to a U.S. audience — that have seeped into the public consciousness as fact.
No one tried to leap a barbed-wire entanglement on a motorcycle to get into Switzerland, said Barris, a reference to the film's climactic scene. The camp was near Sagan, Poland, hundreds of kilometres away from the neutral border.
"The American tunnel king, Charles Bronson, was really Ontarian Wally Floody; the American scrounger in the movie, James Garner, was really Calgarian Barry Davidson; the British document forger, Donald Pleasence, was really Nova Scotia-born Tony Pengell, and on and on," Barris said.
Nobody in the room moved.
During their incarceration, the Americans were kept in a separate wing of the camp from the British, Canadian and Australian flyers and aircrew.
Seventy-six prisoners escaped. Three made it to Allied or neutral countries; 23 were recaptured and put back in POW or concentration camps. The remaining 50 — including six Canadians — were murdered by the Gestapo.
"One U.S. vet said he never knew Canadians were even in the camp," Barris said. "One laughed at how I'd ruined his childhood impression of the story. Another congratulated my offering a truer story."
Scholars say with the passage of time it is going to get harder to keep the record straight.
Copp said there is a market for solid, evidence-based books on Canadian military his, but it's not huge.
"The rest of it that is endlessly on television is very hard to watch because it is so dumbed down that it just seems the fact that it's mentioning Canadians instead of Americans doesn't seem all that relevant because the content value is so slight," he said.
He said Canadians likely know less than they think they do.
"I would think on most of those issues the knowledge is an inch deep and very, very wide."