OTTAWA - As fighter jets roared overheard, soldiers, dignitaries and ordinary Canadians paid tribute to the country's First World War veterans at an "End of an Era" ceremony Friday.

Thousands gathered at the National War Memorial in Ottawa to mark the anniversary of the Battle of Vimy Ridge and mourn the passing of a generation.

The ceremony, like those in cites across the country, follow the death of John Babcock, Canada's last-known veteran of the "war to end all wars."

Hundreds of veterans of later conflicts -- from the Second World War to the war in Afghanistan -- stood at attention and sang as the ceremony opened with O Canada.

Prime Minister Stephen Harper, Gov. Gen. Michaelle Jean, and Gen. Walt Natynczyk, the chief of Defence staff, shook hands with veterans in a range of uniforms.

Four CF-18s soared overhead in a "Missing Man Formation" under grey skies, followed by a 21-gun artillery salute.

Four soldiers in khaki First World War combat uniforms stood sentry around the Tomb of the Unknown Soldier with heads bowed. The tomb holds the unidentified remains of a Canadian soldier killed at Vimy.

Harper said the soldiers of the First World War showed a "fearlessness in war and selflessness in peace" that defined a young Canada in the eyes of the world.

Harper said Canada's youth did not fight to expand our dominion, nor to settle old scores -- they risked their lives "so that other nations could live in the same peace and freedom that had taken such deep root in Canada."

He said they embodied "a greatness that later generations of Canadians have striven to emulate"

The Queen sent a message to Canadians honouring "a truly remarkable generation who helped to end the most terrible conflict the world had ever known."