Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge, attends the Last Post ceremony at the Commonwealth War Graves Commission Ypres Memorial at the Menin Gate in Ypres, on July 30, 2017, as part of the commemoration for the centenary of Passchendaele, the third battle of Ypres, West Flanders. The battle of Passchendaele, also called the third battle of Ypres, took place between July 31 and November 6, 1917 in Passendale, West Flanders.