But the Allied saboteur was a mystery for many years to his own daughter. She had no memories of him growing up. As a child, she only knew him as an ever-present picture in the family home, a pile of medals that included some of France and Britain's highest decorations, and the solemn declarations of dignitaries such as the Governor General that her dad was a hero.
Jacqueline Bieler was little more than three years old when her father parachuted into wartime France to wage war from the shadows as a member of the Special Operations Executive, an elite outfit that then-British prime minister Winston Churchill ordered to "set Europe ablaze."
"We didn't get much information," Jacqueline Bieler recalled in a telephone interview from her Ottawa home. "We had certain generic stuff, like 'your father was a hero.' That didn't satisfy me. I wanted to know who this man was."
It took her much of her life to gradually piece together a portrait of her father, who has streets and plaques in his honour in Europe, as well as a lake in his name on Baffin Island.
What she discovered in research that eventually led her to write a book was a man of intelligence, culture and principle who delighted his friends with his mischievous sense of humour and love of lively debate. Years after he died at the hands of the Nazis, people would still swell with emotion as they talked of him.
She also found out that he was remarkably tough. Decades after Bieler was killed, historians at the notorious Flossenburg concentration camp where he died knew him only as "Guy the Canadian" despite efforts by Nazi torturers to get him to spill Allied secrets. He never even gave them his name.
Born in France to Swiss parents in 1904, Guy Bieler came to Canada in 1924 where he worked as a teacher and then at the Sun Life Assurance Co., where he eventually headed the translation services.
He married his wife Marguerite and fathered two children, Jacqueline and Jean-Louis, before heeding the drumbeat of war in Europe. He originally enlisted in the Regiment de Maisonneuve, shipping out in 1940 to England where he was recruited into the secretive SOE to help organize and lead Resistance networks in the occupied countries.
Bieler, who was blind in one eye from an accident in his teenage years, was the oldest person in the rugged, five-week training course and gained the affectionate nickname 'granddad' from his colleagues. He was seen by his superiors as a natural for the job ahead.
"Keen, intelligent, conscientious, a sound judge of character," wrote Col. M.J. Buckmaster. "Good-natured, absolutely reliable, outstandingly thorough, a born organizer."
Bieler parachuted into France with two other agents in November 1942, dropped off course and, in Bieler's case, on rocky ground that fractured his spine when he landed. Although in pain that would plague him from then on, he resisted suggestions that he return to England and insisted he would complete his mission.
Jacqueline Bieler said all direct communication between her father and his family in Canada ended with the drop into France.
"My mother didn't have any information," she recalled, saying some minimal news was passed to his sister in London by the War Office.
"She would get cards saying he's well and sends his love but those came from London, they certainly didn't come from the field."
Jacqueline Bieler's own life had been uprooted and she split her time between living with her uncle and his wife in Ottawa and returning to Montreal and her younger brother and her mother, who was a "Voice of Canada" broadcasting to the troops on Radio-Canada International.
In France, her father was quickly rallying his Resistance fighters in St-Quentin, northeast of Paris. The area was an important communications and rail link to the Pas de Calais, where the Germans had massed forces against a possible Allied invasion, and to key European industrial centres.
Afflicted with a limp from his parachuting injury, the low-key Bieler would remain inconspicuous, usually dressing as a labourer. The pain from his accident would sometimes have him walking with his head tilted to one side and his shoulder hunched up because of the pain.
"He had a number of different names and that was another thing that absolutely amazed me," said Jacqueline Bieler, who has one of her father's false identity cards, showing him with a lush moustache and the name Maurice Leger.
"I thought to myself, 'how do you remember which name you gave to which community?'"
She said that after the war, however, she found that despite his many names people called him Guy because they knew of a man called "le Commandant Guy," which is the name affixed to three streets in France in his honour.
Although relentless in pursuit of his objective, Bieler was careful to minimize civilian casualties. He scrubbed one mission to destroy a munitions train because it sat on a siding near a residential area. He later destroyed an even bigger train as it passed through the countryside.
He also urged his overseers in London to leave the destruction of railway lines to saboteurs because aerial bombing often resulted in dead civilians. Bieler's approach was to sabotage the trains or unbolt sections of track so it would derail. When trains were blown up, he tried to do it at a bend in the tracks so the crews could jump off.
His efforts paid off, to the frustration of the Germans who hunted him ceaselessly. They came close to him on a couple of occasions when a Nazi tried unsuccessfully to convince him he was a British agent.
Another time, he was tailed by two Germans onto a Paris subway, only evading them by sticking his foot into the doorway of the train as it closed and then forcing it open to jump off as the rail car departed.
But in late 1943, the noose had already begun to tighten. The Germans were employing new radio detection trucks, vehicles that would cruise streets and hone in on clandestine signals.
Even Bieler seemed to sense that his luck was running out. Camille Boury, a Resistance colleague, wrote to Bieler's wife after the war and told her how he'd become reflective after an evening of song, joviality and poetry during their last Christmas together.
After holding his head in his hands for a long time, Bieler had asked for a pencil and wrote the address for Sun Life on the back of some photos.
"Then he said to us literally: 'If misfortune overtakes me some day, write to this address. You will find my wife there. Tell her how I spent Christmas of 1943, describe this evening to her. Tell her how I thought of them'."
In January 1944, a squad of Gestapo agents swooped in on Bieler and another member of his network in a cafe and arrested them. In all, the Nazis snared about 40 Resistance fighters that day.
Once he was in custody, the Nazis savagely beat Bieler, smashing his knee and leaving his face badly swollen. His head was plunged under water in what is now commonly known as waterboarding. He refused to co-operate.
Jacqueline Bieler recalled the account of one fellow detainee who told her after the war he had seen her father in the hallway of the prison after one brutal interrogation attempt and was amazed at his resilience.
"He saw my father coming back from a session and he said he was just a mess," she recalled. "He said he could see the look in my father's eyes saying, 'Don't tell, don't say anything'."
After being shipped to various detention centres, Bieler and 15 fellow prisoners were sent to Bavaria's Flossenburg concentration camp under the "Nacht und nebel" — Night and Fog — designation in April 1944.
"If NN was on your file, you were sent to this special part of the camp and if anyone, Red Cross or anyone else, enquired about you, they were not to get any information," Jacqueline Bieler said. "They were to disappear."
The abuse continued after Bieler was confined to the dank block of 40 windowless cells which also housed other SOE agents and political prisoners such as plotters involved in the July 1944 attempt on the life of German dictator Adolf Hitler.
On Sept. 6, 1944, the Germans decided to cull their prisoners and Guy Bieler was taken from his cell one last time by members of the feared SS. He was walked to the barren courtyard to face a firing squad, not the gas chamber or piano wire usually used to slowly strangle other prisoners.
"This is the only instance known to us of an officer being executed in such circumstances by a firing squad with a guard of honour," Buckmaster wrote to Bieler's wife. "It proves even the Germans could not but recognize his great qualities."
The family got on with life after the war. Jacqueline Bieler said her mother didn't really shed any light on her father's service after he was killed.
"She didn't want to talk about it so we didn't," Bieler said. Her mother remarried about 10 years later.
Jacqueline Bieler didn't start to learn about her father's legacy until 1957, when she was 20 and on a trip to Europe after graduating from university. A relative who had been in British Intelligence suggested she visit the area where her father plied his deadly skills during the war. She was then set up with some of his compatriots.
The response overwhelmed her as the former Resistance fighters celebrated her and took her to places her father frequented, regaling her with stories of the war. The visit also provided her with one of the first indications of an emerging connection with the father she sought to know.
"At one place, I did a gesture with my hands and one man said, 'Oh, your father had that gesture.' It just undid me.
"I'm not just a branch hanging out in limbo on the family tree. I felt connected. I really felt connected."
Jacqueline Bieler said it would be years before she began to feel closure and it would begin to come during a 2005 visit to the Flossenburg camp, where she laid a sheaf of colourful flowers outside the cell where her father had been imprisoned.
"I just got so grief-stricken for what he had to endure," she said. "The whole business he had to go through and then grief for myself because I didn't know this wonderful man growing up."
Jacqueline Bieler, who wrote about her experiences discovering her father in her book "Out of Night and Fog: The Story of Major Guy Bieler," speaks with pride of her father, saying it's a "great honour" to be his daughter.
But she also holds a special place in her heart for the children of war dead in present day who would find themselves in the same situation as she did in the Second World War.
"There's a big ceremony and then there's nothing," said Bieler. "The family is scrambling to pull itself together and deal with the situation. Very often, the children's grief gets lost in this.
"Don't forget the children's grief."