Photo: The Canadian Press. All rights reserved.

Pat Mills, a Second World War bomber pilot, salutes as a squadron of Air Cadets marches by during Remembrance Day Ceremony at the cenotaph in London Ontario, Sunday, November 11, 2012. THE CANADIAN PRESS/ Geoff Robins

Twenty-one gunshots reverberated Sunday off the National War Memorial in Ottawa and 21 times, most of the hushed crowd of thousands collectively flinched at the sound.

Except for the veterans, whose eyes never left the looming cenotaph covered in wreaths and later poppies by those paying tribute to their service in honour of Remembrance Day.

Veterans in wheelchairs wrapped themselves in blue fleece blankets to ward off the chill, sometimes helped to their feet by family members or by the young soldiers in their midst.

"The younger veterans and the older veterans, they meet today in mutual respect and admiration as partners in the battle against evil. They are Canada's best," Rabbi Reuven Bulka, Honorary Chaplain of Dominion Command, told the crowd.

"They fought our fight to ensure freedom and dignity for everyone. They therefore deserve to be celebrated, applauded and eternally appreciated as authentic heroes."

Gov. Gen. David Johnston, who was wearing the blue uniform of the Royal Canadian Airforce, led the national service that also included a military parade, prayers and song.

Among those in attendance was Roxanne Priede, this year's National Silver Cross Mother, picked by the Royal Canadian Legion to attend the ceremony on behalf of all Canadian mothers who have lost children in the service to their country.

Priede shed tears as she lay a wreath at the base of the war memorial. Her son, Master Corporal Darrell Jason Priede, died in a helicopter crash in Afghanistan in 2007.

"May we never forget those who have gone before us, paving the way to a world of greater freedom, more lasting justice and a more profound peace," said Brig. Gen Karl McLean, Chaplain General of the Canadian Forces, who led the ceremony in prayer.

A ceremony held by the City of Toronto was marred by around a half-dozen protesters shouting anti-war slogans during the two minutes of silence.

They were taken away by police, witnesses said.

The ceremony in Hong Kong that Harper attended, took place at a cemetery where 283 Canadian soldiers are buried.

Harper and his wife placed wreaths at the base of the Sai Wan memorial which commemorates those who were killed in the battle of Hong Kong, one of the most catastrophic episodes in Canadian military history.