Britain's Charles, Prince of Wales (2nd L), Britain's Prince William, Duke of Cambridge (3rd L), Canadian Governr General David Johnston (2ndR) and Britain's Prince Harry (L) visit the Canadian National Vimy Memorial during a commemoration ceremony to mark the 100th anniversary of the Battle of Vimy Ridge, in Vimy, near Arras, northern France, on April 9, 2017. REUTERS/Philippe Huguen/POOL