Prince Philip, who retired three years ago, attended a rare royal engagement Tuesday.

The Duke of Edinburgh, 99, was all smiles as he handed over his position as Colonel-in-Chief of the Rifles Regiment to his daughter-in-law, Camilla, the Duchess of Cornwall.

Photo by Samir Hussein-Pool/WireImage/Getty
Photo by Samir Hussein-Pool/WireImage/Getty

The pair were in separate parts of the U.K., with Camilla, who was appointed Royal Colonel of 4th Battalion The Rifles in 2007, being at Highgrove House in Gloucestershire, while Philip appeared in the quadrangle of Windsor Castle.

RELATED: How Prince Harry, Meghan Markle And Archie Are Celebrating Prince Philip’s 99th Birthday

The Duke was greeted by representatives from The Rifles, who thanked him for his work over the past 67 years.

Philip’s appearance comes after he retired from being a full-time working royal in August 2017 after completing an impressive 22,219 solo engagements since 1952.

Since then, he’s made regular appearances at such public events as Princess Beatrice’s secret wedding last week and Prince Harry and Meghan Markle’s wedding in May 2018.

RELATED: Prince Philip Poses With The Queen In New Photo Released To Celebrate His 99th Birthday, Royals Send Well-Wishes

Philip served as a Royal Navy officer during the Second World War and is known to be one of the hardest-working royals.

Click to View Gallery
Prince Philip Passes Away At 99: A Royal Family Photo Album