Prince Harry Opens the Invictus Games

— -- An idea that Britain’s Prince Harry has said he stole from America and “made it bigger” kicked off Wednesday night with his emotional speech in front of thousands of wounded veterans and members of the royal family, minus Duchess Kate.

Harry, who was introduced by first lady Michelle Obama, told the crowd gathered for the start of the inaugural Invictus Games that “lives would be changed” during the athletic competition for wounded veterans from 13 nations.

“Over the next four days, we will see some truly remarkable achievements,” Harry said.

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The prince, 29, was joined at the ceremony in London by his father, Prince Charles, stepmother Camilla, the Duchess of Cornwall, and big brother Prince William.

William’s wife, Kate, did not attend. The Palace announced Monday that she is pregnant with the couple’s second child and suffering from hyperemesis gravidarum, a condition characterized by acute morning sickness.

For Prince Harry, the kickoff to the Games marked the culmination of a yearlong journey that began with a trip to Colorado in 2013 to participate in the U.S. version, called the Warrior Games.

“The Americans made it, I stole it and we made it bigger,” Harry said earlier this week as he handed out the first medals of the Invictus Games for a driving challenge, according to the BBC.

One-quarter of the 400 participants in the Invictus Games are U.S. veterans. Prince Harry has already met with some of the U.S. competitors who flew into London to compete.

“I’ve realized what a difference it can make, using the position to do good,” Harry said of his high-profile role in putting the Games together.

The athletes gathered in London will compete in adaptive sports ranging from wheelchair rugby and basketball to archery and indoor rowing, according to the Invictus Games' website.

The Games' official anthem was penned by Coldplay's Chris Martin and performed Wednesday by singer's from the U.K.'s Armed Forces.

The closing concert, scheduled for Sunday, is expected to include performances by the Foo Fighters, James Blunt and Ellie Goulding, among others.