LONDON, ENGLAND - SEPTEMBER 10:  Prince William, Duke of Cambridge, Camilla, Duchess of Cornwall, Prince Charles, Prince of Wales and Prince Harry stand for the National Anthem at the Queen Elizabeth II Park during the Invictus Games Opening Ceremony on September 10, 2014 in London, England. The International sports event for 'wounded warriors', presented by Jaguar Land Rover, is just days away with limited last-minute tickets available at www.invictusgames.org  (Photo by Chris Jackson/Getty Images)