Queen Elizabeth II’s husband Prince Philip would have celebrated his 100th birthday on Thursday.

The Duke of Edinburgh, who spent more than seven decades supporting his wife, died on April 9th at age 99.

On Thursday, a Buckingham Palace source told People magazine that the reigning monarch, who has been staying at Windsor Castle amid the coronavirus pandemic, will be spending the somber day "privately."

The outlet shared that the 95-year-old has been "quietly coping" with the loss of her beloved husband of 73 years.

The couple married in 1947 and remained together until his death. The queen has described Philip, who became Britain’s longest-serving consort, as her "strength and stay."

PRINCE PHILIP'S CAUSE OF DEATH REVEALED BY QUEEN ELIZABETH'S PHYSICIAN

Prince Philip, the irascible and tough-minded husband of Queen Elizabeth II who spent more than seven decades supporting his wife in a role that both defined and constricted his life, died on April 9. He was 99. (AP)

"There were some things that they had to deal with together that were difficult, but it was a long marriage with a great deal of happiness," Charles Anson, former press secretary to the queen, told the outlet. "He took very seriously his role as a support for the queen as monarch."

Anson insisted that Elizabeth won’t be alone as she remembers Philip behind palace doors.

"She has an enormous amount of family support for her and will also take comfort from the enormity of the support from all over the world," he said.

Buckingham Palace didn’t immediately respond to Fox News’ request for comment.

Elizabeth marked what would have been Philip’s 100th birthday with the planting of a newly bred rose named after him.

PRINCE PHILIP HAD ONE IMPORTANT PIECE OF ADVICE FOR THE YOUNGER ROYALS BEFORE HIS DEATH, FILMMAKER SAYS

Queen Elizabeth II and Prince Philip were married for 73 years. (AP Photo/Eddie Worth)

She was pictured smiling as she accepted the small rose bush, wrapped in brown paper and twine, from the Royal Horticultural Society’s president.

The rose, which is deep pink and dappled with white lines, was newly bred following Philip’s death on April 9 at Windsor Castle.

For every rose sold, the company Harkness Roses will donate 2.50 pounds ($3.50) to a fund aiming to help a million more young people from all backgrounds take part in the Duke of Edinburgh’s Awards, a popular youth award program set up by Philip in 1956.

PRINCE PHILIP, DUKE OF EDINBURGH AND QUEEN ELIZABETH II'S HUSBAND, DEAD AT 99

Queen Elizabeth II watches as pallbearers carry the coffin of Prince Philip, Duke Of Edinburgh into St George’s Chapel by the pallbearers during the funeral of Prince Philip, Duke of Edinburgh at Windsor Castle on April 17, 2021, in Windsor, United Kingdom.  (Photo by Yui Mok-WPA Pool/Getty Images)

The couple’s youngest child, Prince Edward, told the BBC that the royal family would have "loved" the chance for Philip to be able to experience his centenary, even if his late father would have balked at "all the fuss and bother."

"I think he wasn’t really looking forward to the centenary, even if we were," said the 57-year-old. "[But] everyone will have their own memories. He was that sort of larger-than-life person. Once met, never forgotten."

Philip’s funeral occurred a little more than a week after his death. Attendees at St. George’s Chapel were limited to just 30 people as a result of the coronavirus restrictions at the time. Most poignantly, Elizabeth sat alone on one side of the chapel.

Reflecting on his father’s funeral amid the pandemic, Edward said it was an "extraordinary" but "strange" day.

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In this undated handout photo provided by the Duke and Duchess of Cambridge, Britain's Queen Elizabeth and Prince Philip pose with their great-grandchildren. From left, Prince George, Prince Louis, Savannah Phillips (standing at rear), Princess Charlotte, Isla Phillips holding Lena Tindall, and Mia Tindall.  (Duchess of Cambridge via AP)

The couple’s eldest son, Prince Charles, honored his late father on Thursday with a social media post on the Instagram account he shares with his wife Camilla, Duchess of Cornwall.  

It showed a young Charles holding his father’s hand as Philip, wearing a dapper double-breasted suit and sunglasses, greeted him after returning home from a trip to Malta in 1951.

"Remembering The Duke of Edinburgh, on what would have been his 100th birthday," the post said.

Camilla, who opened the British Flowers Week exhibition during a visit to the Garden Museum, was also given a bouquet containing rosemary – a sign of remembrance in honor of Philip.  

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Prince Philip is survived by the queen and their four children — Prince Charles, Princess Anne, Prince Andrew and Prince Edward — as well as eight grandchildren and 11 great-grandchildren. ((AP Photo/Alastair Grant, File))

In his lifetime, Philip devoted his life to royal service, taking on tens of thousands of engagements and accompanying the queen on official visits to some 140 countries. He retired from royal duties in 2017, at age 96.

Philip is survived by the queen and their four children — Prince Charles, Princess Anne, Prince Andrew and Prince Edward — as well as eight grandchildren and 11 great-grandchildren.

The Associated Press contributed to this report.