Britain's Prince Philip has made a rare public appearance amid the coronavirus pandemic.

The 99-year-old attended a military ceremony at Windsor Castle to transfer a long-held ceremonial role to his daughter-in-law Camilla, Duchess of Cornwall.

Philip, who is Queen Elizabeth II’s husband, has been Colonel-in-Chief of The Rifles since 2007 and has served in the same role for earlier regiments that have made up the infantry unit since the ‘50s.

Camilla, wife of Prince Charles, was welcomed as the regiment’s new Colonel-in-Chief in a separate ceremony.

The Duke of Edinburgh retired from public duties in 2017. He was previously photographed at Windsor Castle alongside Elizabeth, 94, to mark his birthday in June. Most recently, he attended his granddaughter Princess Beatrice’s private wedding ceremony on Friday.

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Philip's last major appearance occurred when he was a guest at Lady Gabriella Windsor’s wedding in May 2019.

Philip and Elizabeth share four children, including Charles, 71, who is heir to the throne. The couple also has eight grandchildren and eight great-grandchildren.

At the time he retired from public life, Philip was the patron, president or a member of more than 780 organizations, including many charities. He had given 5,496 speeches, written 14 books and gone on 637 solo visits overseas, in addition to hundreds of trips accompanying the queen.

“I think probably a lot of people don’t know what he’s done because he doesn’t like adulation,” said Ingrid Seward, editor of Majesty Magazine. “He doesn’t like fame. He just gets on with it.’’

In April, Philip took a moment out of retirement to thank key workers for fighting back against the coronavirus pandemic.

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Nov. 18, 2007: HM Queen Elizabeth II and Prince Philip, The Duke of Edinburgh re-visit Broadlands, to mark their Diamond Wedding Anniversary on Nov. 20. The royals spent their wedding night at Broadlands in Hampshire in November 1947, the former home of Prince Philip's uncle, Earl Mountbatten.

Nov. 18, 2007: HM Queen Elizabeth II and Prince Philip, The Duke of Edinburgh re-visit Broadlands, to mark their Diamond Wedding Anniversary on Nov. 20. The royals spent their wedding night at Broadlands in Hampshire in November 1947, the former home of Prince Philip's uncle, Earl Mountbatten. (Photo by Tim Graham/Getty Images)

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“I wanted to recognise the vital and urgent work being done by so many to tackle the pandemic; by those in the medical and scientific professions, at universities and research institutions, all united in working to protect us from COVID-19,” Philip said in a statement shared by the British royal family’s Instagram account.

“On behalf of those of us who remain safe and at home, I also wanted to thank all key workers who ensure the infrastructure of our life continues; the staff and volunteers working on food production and distribution, those keeping postal and delivery services going, and those ensuring the rubbish continues to be collected,” added the royal.

At the time, Newsweek reported the prince was “moved” by the response from the public.

According to the outlet, palace officials noted this surprising move by Philip is likely to be a one-off incident, as opposed to a return to regular royal duties.

“The duke was moved to send a personal message to everyone who is tackling this pandemic, everyone who has made a decision to help in any way they can,” said a palace insider.

“This is a personal message from the duke given these special circumstances.”

The Associated Press contributed to this report.