Canadians were urged to heed the eternal lessons of the Second World War as ceremonies commemorating the 75th anniversary of D-Day were held Thursday in cities across the country.

Veterans and dignitaries including Gov. Gen. Julie Payette attended a ceremony in Halifax marking the June 6, 1944 Allied invasion of France that turned the tide of the war.

Payette began her day on the sands of Juno Beach, and she told the audience in Halifax it was impossible to imagine the horror that unfolded 75 years earlier when the small parcel of land became "hell on Earth."

She thanked the veterans present and stressed the importance of remembering their sacrifice.

"We need to remember, but one, perhaps, of the most important lessons that we get from this is a lesson of hope," Payette said. "The reason, at the end, was to provide a free world, opportunities for all to live a free life, and that is a message of hope."

Havelyn Chiasson, 98, who landed with the first wave of troops on Juno Beach as a 23-year-old with the North Shore New Brunswick Regiment, was among the seven aging veterans introduced in Halifax, each of whom held a rose. The roses were placed alongside a pair of black combat boots symbolizing Canadian soldiers' journey to the battlefield and the comrades left behind.

The program had called for the veterans to hand the roses to a cadet, but those who could were determined to walk over to place the flowers themselves, accompanying the gesture with a salute.

Historian Don Julien, executive director of the Confederacy of Mainland Mi'kmaq, highlighted the contribution of Indigenous soldiers to the war effort. He told the story of Pte. Charles Doucette, a Mi'kmaq man who was captured after landing on June 6, 1944. He and 19 other Canadians were executed at the Abbaye d'Ardenne on orders from a Panzer Division captain, Julien recounted.

In an early morning ceremony at the cenotaph in front of Toronto's Old City Hall attended by veterans, dignitaries and members of the public, Mayor John Tory honoured the 14,000 Canadians who stormed Juno Beach in Normandy.

"Their courage and their determination led to some successes in those early morning hours but that success came at a huge price," said Tory, noting that 359 Canadian soldiers lost their lives on D-Day, including 50 from Toronto. "It would've been hell."

Other Canadians were also marking the anniversary, with the veterans who are the last living link to the largest seaborne invasion in history as venerated guests of honour.

Capt. Martin Maxwell. 95, of the Glider Pilot Regiment, British 6th Airborne Division, shared his story in Toronto about being among the first to land in Normandy the night before the invasion.

"My D-Day started on June 5. Our commanding officer ... came in and said, 'Boys, we've trained for this for a long time. You're the first ones in, so I have to tell you some of you will not be back,"' said Maxwell.

In an interview, Maxwell urged Canadians to keep the lessons of the Second World War in their daily thoughts -- especially given the dwindling number of living people who experienced it firsthand.

"When I look at the world and see mosques, synagogues, churches have been attacked and people murdered, I think back of what I saw ... and they may say, 'What the hell have you done with the tomorrows we gave you?"'

Maxwell urged new generations to take over the torch of freedom and hold it high. Freedom, he said, is precious.

"Once it is lost, it's almost impossible to get back."

As Prime Minister Justin Trudeau and other world leaders gathered in Normandy, Canadians were turning out for wreath laying ceremonies, lectures and displays.

At a solemn event in Ottawa at the National War Memorial, rows of D-Day veterans looked on as representatives from Canada, the United Kingdom and France spoke to the courage of those who stormed the beaches of Normandy.

"We remember their bravery. We remember their fight for freedom. And we remember their sacrifice," said Andrew Leslie, a former general in the Canadian Armed Forces and current parliamentary secretary to the Minister of Foreign Affairs.

"That Canada was assigned its own landing beach, Juno, on D-Day is a testament to what the Allied head command thought of the quality of the men and women who served Canada in uniform and in the merchant marine, and in all walks of life," Leslie said.

After the D-Day assault, code-named Operation Overlord, the ferocious fighting in Normandy would continue for another two months at a cost of more than 5,000 Canadian lives.

Canadian War Museum historian Tim Cook called the 75th anniversary especially significant because the number of surviving veterans is dwindling, with most now in their mid-90s or older.

"We're on the razor's edge, I think of lived memory passing into history," Cook said. "That will change how we think about this war when we've lost our last eyewitnesses to it."

Other planned official ceremonies Thursday included wreath layings in Lethbridge, Alta., and Nordegg, Alta., and in Yellowknife. In Joggins, N.S., a cenotaph re-dedication was planned to honour 13 young men from the community whose names will be added to the memorial, and in Hamilton, Ont., a candlelight ceremony was be held at dusk.

Commemorative D-Day ceremonies are also planned for Saturday in Winnipeg and Calgary.

With files from Christian Paas-Lang