OTTAWA -- Spiritual leaders reflected on the horrors of the First World War while calling for a world of tolerance and peace on Sunday as thousands of Canadians braved the biting cold to remember and honour those who fought to defend such ideals.

While the sun shone down on those assembled around the National War Memorial under a brilliant blue sky, thoughts and memories of the War to End All Wars -- which ended exactly 100 years earlier -- hung heavy over the annual ceremony.

"We gather on this hallowed ground, on which is interred Canada's unknown soldiers, to remember those who made the ultimate sacrifice," Maj.-Gen. Guy Chapdelaine, the military's most senior chaplain, intoned as the crowd stood silently.

"On the centenary of the signing of the armistice, we honour those whose names we know -- and those whose names are known to God alone."

Yet the present and future were also very much in the air as Chapdelaine preached a message of peace and reconciliation amid growing concerns in Canada and around the world that the hard lessons learned a century ago are in danger of being forgotten.

"We know that peace is more than tolerating one another -- it is recognizing ourselves in others and realizing that we are all on the path of life together," Chapdelaine said.

"Lord of justice and peace, enable us to lay down our own weapons of exclusion, intolerance, hatred and strife. Make us instruments of peace that we may seek reconciliation in our world."

The same theme was picked up by Rabbi Reuven Bulka in his own sermon, as he urged Canadians to "reflect on the notion of a world war," and asked: "If the world can be at war, is it not possible for the world to be at peace?

"It is not only possible, it is terribly necessary," he added. "We gather today yearning for a world that is truly at peace. Peace that is highlighted by respect, inclusion, co-operation, helpfulness, kindness and enveloping appreciation."

The messages were timely, coinciding as they did with a gathering of world leaders in Paris to mark the 100th anniversary of the War to End All Wars -- and to discuss efforts to prevent such a terrible conflict from erupting again.

Prime Minister Justin Trudeau was among those in Paris, where nationalism has been identified as a real threat to the fragile state of international peace and stability that has persisted since the end of the Second World War.

Much of that concern centres on U.S. President Donald Trump's actions since coming to power, which include undercutting the NATO military alliance and threatening the rules-based order established after 1945.

The angst was clearly felt by some of those attending Sunday's ceremony in Ottawa as well as other parts of the country, as Canadians from coast to coast to coast marked Remembrance Day at local cenotaphs and monuments.

"As we turn to reflection, we note that over those 100 years we have in fact secured, for ourselves, much progress," Lieutenant Governor of Ontario Elizabeth Dowdeswell said during a ceremony in front of Queen's Park in Toronto.

"Yet today we are living in strange and uncertain times, times when democracies around the world are fragile. We face significant change that all too often threatens to tear us apart."

Royal Canadian Legion member Mark Monk, who attended the Remembrance Day ceremony in Halifax to lay a wreath for Halifax Pride, said Sunday was both a day for remembrance, and a day to think about current conflicts.

"Although we're celebrating the 100th anniversary of the armistice of the end of the First World War, war is still prevalent in all places around the world," he said.

"Even at home there's still conflict of every kind, everywhere: in our own communities, abroad, everybody. And it's the responsibility as a community and as a society to work together to remove conflict, barriers and work together."

While much of Sunday's national ceremony in Ottawa was on the importance of defending international peace, there was also a significant focus on inner peace for those who have served in uniform.

Even before the ceremony, the Royal Canadian Legion had focused attention on the issue by naming Anita Cenerini, whose son, Thomas Welch, took his own life in 2004 after serving in Afghanistan, as this year's Silver Cross Mother.

Welch was the first Canadian soldier to die by suicide after serving in the war in Afghanistan, and Cenerini fought for years to have her son's death recognized as being caused by his military service.

"As we remember those who returned from past wars with injuries, both visible and invisible, inspire us to care for all military personnel who are wounded in body, mind and soul," Chapdelaine said during his sermon.

"Help us to have compassion for our brothers and sisters who, for reasons known and unknown, have considered or attempted suicide. May we be compassionate for the families and friends impacted by these tragedies."

Chief of defence staff Gen. Jonathan Vance praised the Legion for naming Cenerini this year's Silver Cross mother, saying it was long past time for the military to honour those like Welch, "who served honourably and died so as a result of their service.

"Her son committed suicide and is remembered as one of our war dead, and I think that is a very good thing that we recognize her today and his service."

In Montreal, retired major-general Denis Thompson, who served 39 years with Canada's armed forces, said Remembrance Day events are "cathartic and important" for those who served.

Thompson, who commanded troops in Cypress, Bosnia and Egypt's Sinai peninsula, said he remembers the 25 Canadian and dozen American soldiers who died and the 100 that were injured during his time in Afghanistan in 2008 and 2009.

"I can fill those two minutes of silence very easily," he said, "just by cycling through the names of the men that died under my command."

-- With files from Morgan Lowrie in Montreal, Alanna Rizza in Toronto and Alex Cooke in Halifax.