The photo, snapped by his mom Kate Middleton, includes a sweet tribute to Prince Philip.
Prince Harry said of his forthcoming memoir, "I'm writing this not as the prince I was born but as the man I have become."
Princess Eugenie Shares New Photos of Baby August to Celebrate Jack Brooksbank's First Father's Day
The snaps include a candid shot of a father-son napping session!
Baby Lilibet and Archie Will Inherit 'Princess' and 'Prince' Titles When Charles Becomes King
Under current guidelines, great-grandchildren of the monarch are not princes or princesses
The couple is expecting a baby girl—a little sister for Archie!—this summer.
"I want to give you a big, squeezy cuddle," Kate told 5-year-old Mila.