Gen. Tom Lawson, Canada's top military commander, was thumbing through his grandfather's First World War diaries when he had a startling moment of kinship with a man he knew only as a "tough" old guy.

One of the journal's entries told of a soggy day in southern England in 1918 as newly minted flight-lieutenant Norman Moran endured the rigours of Royal Flying Corp training at the controls of Sopwith Camel biplane, a notoriously tricky fighter plane.

Moran was preparing to fight high above the grinding morass of trenches and shell fire, but ultimately didn't get the chance.

The war ended before he could get to France, but even still he lost two dozen friends and colleagues to training accidents on the Salisbury Plains southwest of London.

One of the under-appreciated legacies of the war to end all wars is how it spawned a culture of service in succeeding generations, with many of those in uniform today tracing their ancestry back to that calamitous time.

Reading through the time-worn passages, Lawson said he recognized his grandfather buried much of his grief, but the diaries still gave him a glimpse of an anxious young man struggling to master what was then a dangerous machine.

"It was a connection I'd never felt to my grandfather," Lawson said of the diaries, which he only received last Christmas.

"His experiences in flight training were very much like my experiences in flight training. You (start) with terrible self- confidence and you have to build that self-confidence to become a pilot."

Moran, Lawson's maternal grandfather, went on to serve in the Second World War as a squadron commander alongside U.S. forces in Alaska. Both Lawson's father and his paternal grandfather also served in uniform.

Lance Cpl. Thomas Lawson started out as driver, but ended up serving as a rifleman during the exceptionally bloody last 100 days of the First World War, when the 100,000-strong Canadian Corps served as the shock troops of the British Army on the Western Front.

Other soldiers, notably retired lieutenant-general Andrew Leslie, also trace their lineage back to the war.

Both of Leslie's grandfathers, former general Andrew McNaughton and Brooke Claxton, served with distinction in the artillery. Leslie's father was also a gunner in Korea.

Historian Jack Granatstein said the war helped foster a legacy of service in a number of families, but the phenomenon is most pronounced among junior non-commissioned officers, the backbone of the military.

"Seems to me I can think of a large number of sergeants who sent their kids to (Royal Military College) so that they would keep the connection but do it as an officer," said Granatstein, who penned the book The Greatest Victory: Canada's One Hundred Days, 1918.

"I'm not sure you can do that in the UK, for example. I don't think the son of a sergeant could end up at Sandhurst (Britain's officer training school). But ours is a more democratic society. Getting into RMC is a matter of having sufficient grades."

Being the grandson of a lance corporal, Lawson, who was appointed chief of defence staff in October 2012, embodies that spirit to a certain extent. He rose to become Canada's top military commander.

On Friday, the military marked the milestone event of 50 years since the creation of the chief of defence staff position.

Lawson counts former general Sir Arthur Currie, the commander of Canadian Corps and the architect of the victory at Vimy Ridge, as one of his heroes.

The wars Currie fought off the battlefield, with his allies and most notably with the volatile Sam Hughes, Canada's minister of militia and defence, have been significantly instructive for Lawson.

"He teaches me today that there things that are far more important than simply following orders," he said. "There is ground for a chief of defence staff to die on, so to speak, in defence of the Canadian Armed Forces, but (also) in defence of Canadians and Canadian interests."

There's another interesting parallel, Granatstein says.

Lawson is struggling today with a shrinking defence budget in much the same way Currie and other soldiers from the First World War generation had to fight to preserve what was built up during the conflict.