
Britain's Catherine, Duchess of Cambridge, King Philippe of Belgium, Britain's Charles, Prince of Wales, Queen Mathilde of Belgium, Britain's Prince William, Duke of Cambridge and British Prime Minister Theresa May participate in the commemorations at The Tyne Cot Commonwealth War Graves Cemetery in Zonnebeke, Belgium, on Monday July 31, to mark the 100th anniversary of the Third Battle of Ypres -- one of the deadliest battles of World War I.

Prince Charles delivers a speech during the event in Zonnebeke on July 31.

Veterans and active duty soldiers from The Royal Regiment of Scotland march in a parade in Crieff, Scotland, on Sunday, July 30.

Veterans stand at attention during a service in Crieff.

Governor of Edinburgh Castle, Maj. Gen. Mike Riddell-Webster, lays a wreath by a drum altar in Crieff.

Visitors and tourists walk among actors as they recreate scenes from the Battle of Passchendaele on July 30 in the Ypres Salient battlefields area of Belgium. Dignitaries and descendants of those who fought gathered to mark the centenary of the Third Battle of Ypres.

A Dutch group of professional reenactors called Tommy's Sisters recreate life for the medical staff during World War I on July 30 in Ypres. The group portrays British nurses and others from the Great War.

An actor runs through the battlefield during the Passchendaele battlefield experience on July 30.

Poppies with personalized messages from members of the British public are seen at the Tyne Cot Cemetery on Saturday, July 29 in Ypres, Belgium.

A photo dated July 31, 1917 shows Allied troops at the Yser Canal in Belgium on the opening day of the Third Battle of Ypres during World War I.

British troops are seen with mules and a wagon in front of the ruins of the medieval Cloth Hall in Ypres after the Third Battle of Ypres in 1917.