A spectacular ceremony in Orlando launches the start of four days of sporting competition between injured servicemen and women and veterans from 14 countries.
During the games, more than 500 competitors from countries including Italy, Germany, Australia, Estonia, Jordan and the UK and Afghanistan will compete in 10 events - archery, indoor rowing, powerlifting, road cycling, sitting volleyball, swimming, athletics, wheelchair basketball, rugby and tennis.
The flags of each nation were paraded into the performance arena by cadets from the Liberty High School Army Junior Reserve Officer Training Corps. They were joined by the competitors and each nation was cheered by the crowd as it was announced.
Prince Harry spoke to the crowd of veterans, competitors, families and friends to launch the Games.
I cannot tell you how proud and excited I am to open the second Invictus games here in America
The Invictus flag, which had travelled from the UK to the US, and made a stop at the White House, made the final leg of its journey by helicopter and was brought into the arena by US Staff Sergeant August O'Neill - who has battled back to full health and returned to service after losing a leg, due to a bullet injury.
US first lady Michelle Obama and former US president George Bush, both long-term supporters of America's military veterans, joined Prince Harry, as did Defence Secretary Michael Fallon, in the audience of thousands which filled the champion stadium at the ESPN Wide World of Sports complex, home to the games.