Six MILLION Brits fought in World War I, and Britain lost about twice as many soldiers in World War I than it did in World War II.
Today, there are only ten British men who are still alive who fought in WWI. One of them is 109 - he's the oldest man in Britain.
They starred in a recent must-see BBC documentary called The Last Tommies, telling us all about their experiences of WWI.
Today, they are taking part in the Remembrance Day ceremonies -
Oldest War Veteran Lays Wreath in France
Lest we forget: A two-minutes' silence will be held at 11am to mark the Armistice
Britain's oldest war veteran is to mark Armistice Day by laying a wreath for fallen comrades at a war memorial in France.
First World War veteran Henry Allingham, 109, the last survivor of the Battle of Jutland and the last surviving founder member of the Royal Air Force, has travelled to St Omer, near Calais, to honour those who died.
Mr Allingham, from Eastbourne, East Sussex, is guest of honour at a wreath laying service at the first permanent memorial to British air personnel who served on the Western Front, located just outside the French town.
He will be joined for the ceremony by Air Vice Marshall Peter Dye, the RAF's deputy commander-in-chief and chief of staff, and a dozen aircraft engineer trainees from RAF Cosford, near Wolverhampton.
French war veterans and local dignitaries will also gather at the memorial built at the aerodrome which during the Great War became the most important British air base in France and Belgium, and where the initially small British air services developed into the RAF.
Despite his age, Mr Allingham plans to walk from his wheelchair to the air memorial to lay a wreath at 10.30am before driving back to the centre of St Omer to salute the fallen at the town's own war memorial on the 11th hour of the 11th day of the 11th month.
Dennis Goodwin, the chairman of the World War One Veterans' Association, said: "Henry is very much looking forward to the ceremony because he knows that he is the ambassador in a way to all the veterans in the UK.
"He is the flag carrier for them and is very proud of what he can do.
"It also gives him a great sense that there is a tomorrow, a focus for going on.''
Mr Allingham, who received a standing ovation at the unveiling of the St Omer air services memorial on Armistice Day last year, is also planning to attend the Cenotaph in Whitehall on Remembrance Sunday.
More than 50 British air squadrons were based at some point at St Omer, which was both an operational station and a major maintenance depot, home to 4,000 personnel by 1918.
The struggle for air superiority came at a high cost, with British airmen maintaining a relentless offensive despite suffering periods of technical and tactical inferiority to the Germans, culminated in the notorious "Bloody April'' of 1917 when more than 8,000 airmen were killed or injured.
The Royal Air Force, formed just before WWI (but didn't become known as the RAF until WWI) when flight was still in its infancy, is the oldest air force in the world.