(CNN) -- The handful of surviving World War I veterans were celebrated Tuesday as part of 90th anniversary commemorations of the conflict that was meant to "end all wars."
French President Nicolas Sarkozy and his wife, Carla Bruni-Sarkozy, at a WWI memorial in France.
France's President Nicolas Sarkozy, Britain's Prince Charles, German Parliament Speaker Peter Muller and Australia's Governor General Quentin Bryce held a joint remembrance ceremony at Fort Douaumont, where more than 300,000 men were slaughtered over 300 days during the Battle of Verdun.
The quartet laid wreaths at the foot of a massive French flag that soared over the ground between two large fields of crosses marking graves.
Hundreds of veterans from other wars watched on as the solemn ceremony progressed. Watch more on the ceremony in France »
Smaller memorials were planned in towns across Britain and France to remember the fallen.
The armistice ending the "Great War" came into effect at the 11th hour of the 11th day of the 11th month, and the day has since been used to remember all war dead. Watch more on surviving WWI veterans »
There are few remaining WWI veterans.
Erich Kastner, the last German veteran, died January 1 this year, aged 107.
The last French soldier, Italian-born legionnaire Lazare Ponticelli, survived him by two months, dying March 12 aged 110.
Four British veterans are still alive after joining other Commonwealth, French, Russian and Italian troops in the fight against Germany and her allies.
Naval air service mechanic Henry Allingham is the oldest, having turned 112 in June.
He served in the 1916 Battle of Jutland in the North Sea before joining the new Royal Air Force at the Somme.
Claude Choules, 107, a Royal Navy man, served on board HMS Revenge and now lives in Australia. Watch the UK ceremony »
Fellow seaman, Bill Stone, 108, served as a stoker aboard the battlecruiser HMS Tiger.
Harry Patch, 110, fought in the trenches near the Belgian town of Ypres in the Duke of Cornwall's Light Infantry. He was hit by shrapnel in the lower abdomen but survived.
In his 2007 autobiography, "The Last Fighting Tommy," written with Richard van Emden, he said "war is organized murder" before adding at a memorial event last month: "It was not worth it. It was not worth one, let alone all the millions."
A fifth surviving man, Netherwood "Ned" Hughes, was called up by the British Army as a driver in 1918, but the war ended while he was still in training.
Patch, Stone and Allingham took part in a London ceremony at the Cenotaph, near the Houses of Parliament, laying wreaths.
The war's defining moment came in 1917, when the United States joined Britain and France.
Frank Buckles, now 107 and living in West Virginia, is the U.S.'s sole remaining veteran. He lied about his age and signed up as a 16-year-old ambulance driver.
All About World War I