The Duke of Cambridge donned his RAF uniform to deliver a speech via video message to mark the 100th anniversary of the Royal Australian Air Force on Wednesday.
Prince William, 38, who has served as an RAF search and rescue helicopter pilot and then with the air ambulance, spoke of the "special bond" between the two services.
WATCH: Prince William dons military uniform to mark 100th anniversary of Royal Australian Air Force
The Duke paid tribute to serving personnel, saying: "The 100th anniversary of the Royal Australian Air Force gives us an opportunity to reflect on the service, courage and sacrifice made by generations of Air Force men and women in Australia and around the world.
"In conflict and in peace, the Royal Australian Air Force has developed an outstanding reputation for resilience, innovation and dedication to duty.
"Over the last 12 months, Australia has faced the challenges of terrible bushfires and a global pandemic. The Royal Australian Air Force has once again shown its ability to respond quickly to supporting Australians in need."
William, Kate and George visited Australia in 2014
William and wife Kate had reportedly been due to visit Australia in 2020 but their trip was cancelled amid the pandemic. The couple travelled to the country in 2014 for an official tour with a then eight-month-old Prince George.
The Duke added: "During my own service I had the pleasure of meeting many serving Australians and have seen first-hand the special bond shared between our two services. More recently, Catherine and I have been welcomed at a number of Royal Australian Air Force bases and have enjoyed hearing stories from serving personnel.
"While your second century will be very different to the first, I am sure that future generations of servicemen and women will carry forward the proud legacy established by hard working and courageous Australians during the first 100 years of The Royal Australian Air Force."
The Queen at the service in Runnymede
William's video message followed his grandmother the Queen's first public outing of 2021, during which she marked the anniversary at the CWGC Air Forces Memorial in Runnymede.
The monarch, 94, wearing a lime green and ivory Angela Kelly coat and her Australian Wattle brooch, attended a special service and met serving RAAF personnel.
The Queen last publicly stepped outside Windsor Castle in December 2020 when she and senior members of the royal family thanked local key workers. Prior to that, the monarch attended the Remembrance Sunday service in central London in November 2020.
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