This, her first military post as a member of the Royal Family, was given to her in December 2015 upon Prince Philip relinquishing the position and passing it over to her.
Meghan wore a long-sleeved, full-skirted black Dior dress with a bateau neckline, topped off with a Stephen Jones fascinator.
Attending the RAF 100 ceremonies was especially poignant for Kate, as she is the Honorary Air Commandant of the Royal Air Force Cadets.More news: Kevin Anderson beats John Isner in Wimbledon semifinals
Meghan and Harry will head straight from the service to Dublin for a two-day tour.More news: China's trade surplus widens in June as imports drop
Prince Charles, Camilla, Duchess of Cornwall, and Queen Elizabeth II also attended the event at Westminster. Here are some choice shots, including adorable little girls meeting Kate Middleton, a little boy in a corgi suit meeting Prince Charles, and Princess Diana letting a toddler play with her necklace.
The official Sussex itinerary in Ireland includes parties, sports, meetings with Irish Prime Minister Leo Varadkar and President Michael Higgins, and visits to see the historic Book of Kells in Trinity College's famed Old Library, to pay respects at the nearby memorial to the Irish Famine and to explore the Irish Emigration Museum. The Duchess of Cambridge never bows out from re-wearing designer duds for royal outings and does so in the chicest manner.
The queen, 92, front and center for the RAF events.More news: Putin meeting won't have 'Perry Mason' moment