She was joined by her husband, the Duke of Edinburgh, and her grandson, the Duke of Cambridge, at the dedication of the Flanders Fields Memorial Garden at Wellington Barracks in central London.
Wearing a coat echoing the camel colour of the uniforms worn by soldiers in the conflict 100 years ago, the Queen - commander-in-chief of the British armed forces - was among those to place a wreath at the garden in recognition of the sacrifice made by so many.
The garden, a short walk from Buckingham Palace, was created with soil taken from 70 battlefields and war grave cemeteries in Flanders, Belgium, where millions died.
The official opening marked a year-long journey to collect and lay the soil, gathered by schoolchildren from the UK and Belgium in 70 sandbags.
Philip, in his role as senior colonel of the Household Division and colonel of the Grenadier Guards, was also present for the soil-gathering ceremony in Ypres on Armistice Day last year.
The king of Belgium and the grand duke of Luxembourg were among those visiting London to see the gardens opened today, accompanied by music from the band of the Grenadier Guards and the state trumpeters of the Household Cavalry.
CONNECT WITH THE SCOTSMAN
• Subscribe to our daily newsletter (requires registration) and get the latest news, sport and business headlines delivered to your inbox every morning
A bugler performed the Last Post as an audience of dignitaries looked on in sombre reflection.
Addressing the audience, curator Andrew Wallis said: “This project is about honouring the fallen of the Great War.
“The design of the garden is full of meaningful features. It is a wonderful fusion of Belgo-Anglo craftsmanship.”
Designed by Belgian architect Piet Blanckaert, the garden was inspired by the design of the First World War memorials and carries the insignia of all the seven guards regiments whose members sacrificed their lives on the battlefields.
It features levels of soil designed to replicate the final resting place of fallen soldiers, as well as a central circular bed and an inscription from John McCrae’s In Flanders Fields.
It also includes a bench made from Flemish bluestone and trees indigenous to the battlefields.
Major General Edward Smyth-Osbourne, general officer commanding the Household Division and Headquarters London District, said: “The foot guards regiments are made up of Grenadier Guards, Coldstream Guards, Scots Guards, Irish Guards and Welsh Guards and so represent all four nations of the United Kingdom.
“Taken with the two mounted regiments from the Household Cavalry, the Life Guards and the Blues and Royals, they also represent both cavalry and infantry.
“In the same way that these 70 sandbags of soil represent all the battlefields of Flanders, these seven regiments represent all the British expeditionary forces who gave their lives for our freedom.”
William and his brother Prince Harry were due to hold a royal reception for 300 guests who helped create the memorial to the war dead.
SCOTSMAN TABLET AND IPHONE APPS