Three days after the birth of his first child, the Duke of Sussex is already showing how proud he is to be a father.

On Thursday, Prince Harry attended the launch of the Invictus Games – a multi-sport event created by the Duke of Sussex for injured service members and veterans – while wearing a jacket printed with the name “daddy.”

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Foto: The Duke of Sussex wears a jacket printed with the phrase “I Am Daddy.”sourceChris Jackson/Getty Images

He wore the navy-blue jacket while riding a bike during a tour of Sportcampus Zuiderpark, a sports complex within The Hague.

The jacket technically reads "Invictus Family Daddy," though the "I" in "Invictus" and "am" in "Family" are highlighted in yellow.

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Foto: Prince Harry rides a bike at the launch of the 2019 Invictus Games.sourceChris Jackson/Getty Images

Read more: 35 adorable photos prove that Prince Harry will definitely be a fun dad

Harry's wife, Meghan Markle, gave birth to the couple's first child, a baby boy named Archie Harrison Mountbatten-Windsor, on Monday. The Duke and Duchess of Sussex introduced their son to the world during a photo call at Windsor Castle on Wednesday.

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Foto: Meghan Markle and Prince Harry hold their newborn son.sourceWPA Pool/Getty Images

"It's magic, it's been pretty amazing," Markle said during the photo session on Wednesday. "I have the two best guys in the world, so I'm pretty happy."

Harry also said the couple is unsure yet as to who the baby resembles most.

"Everyone says that babies change so much over two weeks - we're basically monitoring how the changing process happens over this next month," the duke said, adding that "he's already got a little bit of facial hair."