(Front row, from L) Britain's Camilla, Duchess of Cornwall, Britain's Prince Charles, Prince of Wales, Belgium's Princess Astrid, Hereditary Grand Duke of Luxembourg Guillaume and his wife Hereditary Grand Duchess Stephanie attend the re-opening ceremony of Hougoumont Farm, a farm that played a critical role in the outcome of the Battle of Waterloo in Braine-l'Alleud, Belgium, on June 17, 2015. Britain's Prince Charles and his wife Camilla on June 17 unveiled a memorial to the allied soldiers who defeated French emperor Napoleon's forces at the Battle of Waterloo two hundred years ago. The royal couple visited the renovated Hougoumont farmhouse where allied forces fought off a bloody French advance on June 18, 1805, in one of the most decisive moments in the battle. AFP PHOTO / POOL / EMMANUEL DUNAND        (Photo credit should read EMMANUEL DUNAND/AFP/Getty Images)