The event focused on paying respect to the service members as the operation is coming to an end after 75 years. It was a homecoming for William and Kate, who were based in Royal Air Force Valley from 2010-13 as the Duke worked as helicopter co-pilot for the Search and Rescue Training Unit.
"During this time, His Royal Highness undertook a total of 156 search and rescue operations, resulting in 149 people being rescued," the royal palace wrote on Instagram.
"The Duke and Duchess of Cambridge meet current and former @royalairforceuk Search and Rescue personnel at a reception held in the Officers' Mess," the palace wrote in another post.
On the reflective day, William's former squadron commander, Sparky Dunlop, told reporters the royal was a "very good pilot," adding: "He would live and work with his crew, go on rescues with his crew, eat with his crew. He was just another one of the guys."