He will open the nearby British Memorial Poppy Garden in Passchendaele Memorial Park alongside The King and Queen of Belgium. "Members of our families; our regiments; our nations; all sacrificed everything for the lives we live today". The Menin Gate has on it the names of the 54,391 British dead with no known grave.
"I'm very thankful to the World War 1 Commemorative Committee, chaired by Cllr MacPherson, who are organising this important date. One hundred years on, we still stand together, gathering as so many do every night, in remembrance of that sacrifice".
Earlier on Sunday, The Duke and Duchess of Cambridge attended the Last Post ceremony at the Commonwealth War Graves Commission Ypres Memorial.
Picture the First World War and one nearly certainly thinks of "mud, trenches, and pointlessness".
More than half a million Allied and German troops were killed or wounded in the World War I battle in western Belgium, also known as the Third Battle of Ypres.
The aim was to drive the Germans from the Belgian ports on the English Channel, where German U-boats lurked. The battle had lasted for three months, caused 325,000 Allied and 260,000 German casualties and advanced the Allies just 5 miles.
On Monday, the anniversary of the start of the battle, commemorations will continue with a special service held at Tyne Cot cemetery in Belgium, where thousands are buried and commemorated.
Serving military personnel and descendants are expected to read out letters and diaries from their ancestors in tribute to those who fought at Passchendaele.
One of the more unique commemorative performances involves a band of living history actors, 'Tommy's Sisters, ' who have recreated the battle over the weekend.