A Canadian serviceman leans on the Tomb of The Unknown Soldier to place his poppy following Remembrance Day ceremonies in Ottawa on Tuesday. (Tom Hanson/Canadian Press)

Thousands of people braved grey skies and damp winds to crowd around the National War Memorial in Ottawa on Tuesday to pay tribute to Canada's war heroes in the country's largest Remembrance Day ceremony.

The day marked the 90th anniversary of the end of the First World War, which ended at the 11th hour of the 11th day of the 11th month in 1918. Ottawa's ceremony paid special tribute to that war.

Canadian Forces chaplain Brig.-Gen. David C. Kettle led a prayer at the ceremony calling on Canadians to "honour and pray for those brave soldiers, sailors and air personnel" who served in the Great War.

"What they lived through during times of great conflict, strife and war are not just memories," Kettle said. "The sounds of war, the horror of the battle, echo in their minds as real as it was yesterday. They know the cries of suffering and pain and it's etched on their faces and in the tears in their eyes this day."

Veterans risked their lives "in the name of a better world so that the nightmare of war and death would end," he said. The gift they gave to Canada was the nation itself, he added.

100,000 Canadian soldiers killed

Roads were closed within a three-block radius of the memorial as young and old crowded into the capital's downtown.

The average age of veterans of the Second World War is 84 and many claimed the lines of chairs that were closest to the memorial, which also hosts the Tomb of the Unknown Soldier. Many more veterans stood at attention with rows of young cadets and other military personnel.

More than 100,000 Canadians soldiers have died in various conflicts since 1899, including:

• More than 240 in the Boer War.
• More than 66,000 in the First World War.
• More than 44,000 in the Second World War.
• 516 in the Korean War.
• 121 in peacekeeping missions.
• 97 in Afghanistan.

Kettle also prayed for the safety of Canadians currently serving in conflict zones. "Do not take them for granted but sincerely honour them as modern-day heroes," he said.

Sentries stand on guard in front of the National War Memorial in Ottawa during Remembrance Day ceremonies on Tuesday. (CBC)

Avril Stachnik served as this year's Silver Cross mother and laid a wreath on behalf of all mothers who have lost children in wars.

Stachnik's son, Sgt. Shane Stachnik, died in September 2006 during an Operation Medusa battle with Taliban fighters in southern Afghanistan.

"This is just a tremendous honour," Stachnik told CBC News before the ceremony. "I just couldn't hardly fathom how they chose me as their Silver Cross mother but I am very honoured."

"We've all been there," Stachnik said. "We all have gone through the same thing and all I can say is keep praying for your kids. Don't ever ... forget that they're there and there for a job, and they're there because they want to be there to help people."

The Last Post played as the Peace Tower clock crept towards 11 a.m. ET. As the bells tolled out the hour, two minutes of silence fell over the downtown, ending with a bagpipe lament, followed by The Reveille, the reading of one stanza of the poem For the Fallen and four CF-18 jets flying over the downtown.

Meanwhile, down the street at Parliament Hill, artillery pieces fired a salute 21 times. At the Canadian War Museum, a beam of sunlight streamed into a specially constructed chamber, Memorial Hall, illuminating a headstone of an Unknown Soldier at exactly 11 a.m.

John Babcock, 108, is Canada's only remaining First World War veteran. (CBC)

More than 600,000 Canadian soldiers volunteered to go overseas for the Great War. In addition to those who died, more than 172,000 were wounded.

Only one Canadian veteran from the First World War is still alive — John Babcock, 108, who was born on an Ontario farm and lives in the United States.

Babcock participated in Ottawa's ceremony by video conference, "passing" a lit torch, a reference to Lt.-Col. John McCrae's famous poem, In Flanders Fields.

"We must never forget our fallen comrades. I pass this torch of remembrance to my comrades. Hold it high," Babcock said.

Beginning with a veteran from the Second World War, the torch was handed to a Korean veteran, a peacekeeping veteran and a "modern-day" soldier who served in Afghanistan, before it was placed at the base of the memorial.

Spontaneous act of remembrance

Prime Minister Stephen Harper greets veterans following Remembrance Day ceremonies in Ottawa. (Tom Hanson/Canadian Press)As dignitaries finished placing their wreaths at the steps of the memorial, the parade of colours and music streamed by a platform where Prime Minister Stephen Harper and Gov. Gen. Michaëlle Jean, who had presided over the ceremony, stood. Military personnel, cadets, veterans and RCMP officers saluted as they marched by.

The thousands who had gathered for the ceremony then began to stream toward the memorial to place their poppies on the Tomb of the Unknown Soldier, covering it in the red flowers.

"It seems to be a most appropriate act at the individual level," said retired Maj. George Pearce. "But its beauty is in its spontaneity — that was never orchestrated, never planned. It just happened."

Gen. Walter Natynczyk, Canada's new chief of defence staff, said he was inspired by Canada's veterans.

"Canadians support their veterans," Natynczyk said. "They recognize the fight that they had in their day in uniform that brought this country together, battles that were won like Vimy Ridge, the Battle of the Atlantic, Battle of Britain."