Prince William will be the best man at Prince Harry and Meghan Markle's wedding on May 19, the Kensington Palace said early Thursday. The Duke of Cambridge said he was "honored" that his brother asked him to be by his side on the special day.

The announcement comes a day after Prince Harry, his fiancée and dad for the third time, Prince William, were spotted together observing Anzac Day Wednesday. They were photographed attending an Anzac Day Service of Commemoration and Thanksgiving held at London's Westminster Abbey.

Prince Harry was Prince William's best man at his wedding to Kate Middleton in 2011.

The 33-year-old will marry the "Suits" actress at St. George's Chapel at Windsor Castle. The location of the wedding is a much smaller venue than Westminster Abbey, where Prince William, married Kate Middleton. 

More than 600 guests, which will not include any politicians, have been invited to the ceremony with 1,000 members of the public. 

"It has been decided that an official list of political leaders — both U.K. and international — is not required for Prince Harry and Ms. Markle's wedding," a Kensington Palace spokesman said earlier this month. "Her Majesty's Government was consulted on this decision, which was taken by the royal household."

Earlier this month, the palace also announced that Prince Harry and Markle have asked their guests not to give them any wedding gift but instead prefer donations to charity. 

"Prince Harry and Ms. Meghan Markle are incredibly grateful for the goodwill shown to them since the announcement of their engagement and are keen that as many people as possible benefit from this generosity of spirit," Kensington Palace announced. "The couple have therefore asked that anyone who might wish to mark the occasion considers making a donation to charity, rather than sending a wedding gift."