Britain’s Queen Elizabeth II died on Thursday at the age of 96.

The royal family posted a statement on their official site saying: “The Queen died peacefully at Balmoral this afternoon. The King and The Queen Consort will remain at Balmoral this evening and will return to London tomorrow.”

Her 73-year-old son Prince Charles automatically becomes king, though the coronation might not take place for months. It is not known whether he will call himself King Charles III or some other name.

The BBC played the national anthem, “God Save the Queen,” over a portrait of her in full regalia as her death was announced, and the flag over Buckingham Palace was lowered to half-staff as the second Elizabethan age came to a close.

In a statement, Charles called the death of his mother “a moment of the greatest sadness for me and all members of my family,” adding: “I know her loss will be deeply felt throughout the country, the Realms and the Commonwealth, and by countless people around the world.”

Elizabeth had marked 70 years on the throne in February 2022. She had increasingly handed over duties to her heir, Prince Charles, and other members of the royal family in recent months as she struggled to get around.

Britain’s longest-serving monarch is the only sovereign most Britons have ever known. The queen had been a constant presence as Britain navigated the end of empire, the swinging ’60s, the labor strife of the 1980s, international terrorism, Brexit and the COVID-19 pandemic.

Buckingham Palace had said on Sept. 8 that the queen was under medical supervision because doctors were “concerned for Her Majesty’s health,” as members of her family traveled to be with the 96-year-old monarch in Scotland.

“Following further evaluation this morning, the Queen’s doctors are concerned for Her Majesty’s health and have recommended she remain under medical supervision,” the palace said in a statement that sparked deep concern.

The announcement came a day after the queen canceled a meeting of her Privy Council and was told to rest. Earlier in the week, she had presided over the ceremonial handover of power to new Prime Minister Liz Truss at her summer residence at Balmoral Castle in Scotland.

Queen Elizabeth II ascended to the throne in 1952 after the death of her father, King George VI, and five years after marrying Prince Philip, also known as the Duke of Edinburgh, at London’s Westminster Abbey. She and Prince Philip have four children, eight grandchildren and 12 great-grandchildren.

Prince Philip died at age 99 in April 2021.

The youngest great-grandchild, the daughter of Princess Beatrice and husband Edoardo Mapelli Mozzi, was born Sept. 20, 2021.

The queen had delegated one of her most important public duties to Prince Charles in May, having him preside over the state opening of Parliament and delivering the Queen’s Speech laying out the government’s legislative program. The event is a symbol of the monarch’s constitutional role as head of state and is accompanied by centuries of tradition designed to demonstrate the strength of Britain’s political institutions.

The queen was diagnosed with COVID-19 in February 2022, shortly after both her eldest son Prince Charles, 73, and her 74-year-old daughter-in-law Camilla, Duchess of Cornwall, also contracted the disease.

In remarks released for the 70th anniversary of her rule, the monarch expressed a “sincere wish’’ that Camilla should be known as “Queen Consort” when her son succeeds her as expected. With those words, Elizabeth sought to answer once and for all questions about the status of Camilla, who was initially shunned by fans of the late Princess Diana, Charles’ first wife.

After recovering from COVID, the monarch made her first public appearance in months at a service of thanksgiving for her beloved husband, Prince Philip. She entered the church on the arm of her second son, Prince Andrew, then separated from him to walk to her seat alone, easing concerns about her health. The monarch was deeply involved in planning the service, which included hymns and tributes from Philip’s charities. Such touches weren’t possible during his funeral because of rules surrounding the pandemic.

About 1,800 family members and guests attended the memorial. Only 30 people attended Philip’s funeral, conducted under the strict COVID-19 lockdown rules then in place that forced the queen to sit alone wearing a black mask as she mourned the loss of her husband, who she called her rock.

The queen missed the traditional royal garden party season in 2022 after it resumed for the first time in three years. The guests, who have all served their community in different ways, had previously had the opportunity to speak with the queen and other royal family members at the parties. The queen was represented by other members of the royal family.

A fixture in the life of the nation, Elizabeth was in robust health for most of her reign and had been photographed riding a horse as recently as 2020. In the past year, she had been seen using a walking stick at a major public event for the first time (a Westminster Abbey service marking the centenary of the Royal British Legion in Oct. 2021) and she spent a night in a London hospital for unspecified tests.

The queen’s doctors ordered her to rest afterward, and she was forced to cancel appearances at several key events, including Remembrance Sunday services and the COP26 climate conference in Glasgow, Scotland, in November. The queen also missed out on a Remembrance Sunday service to pay tribute to Britain’s war dead in November 2021 because she had sprained her back. The service is one of the most important events on the monarch’s calendar and was meant to be her first public appearance after taking a few weeks off to rest under doctors’ orders.

The queen served in World War II as an army driver and mechanic and is head of Britain’s armed forces. She attaches great importance to Remembrance Sunday, a solemn ceremony to remember the sacrifices made by fallen servicemen and women. The national service, which follows Armistice Day on Nov. 11, is traditionally marked by the wearing of poppies and a national two-minute silence observed at 11 a.m.

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• UK’s Princess Beatrice gives birth to daughter
• Judge orders Philip’s will sealed to protect royal ‘dignity’
• Queen enters ‘twilight’ of reign after farewell to Philip
• Prince Philip laid to rest at Windsor Castle

Despite her advanced age, the monarch politely declined the honor of being named “Oldie of the Year” by a British magazine. The magazine published the queen’s response to its suggestion that she follow in the footsteps of former recipients, such as actor Olivia de Havilland and artist David Hockney.

“Her Majesty believes you are as old as you feel, as such The Queen does not believe she meets the relevant criteria to be able to accept, and hopes you will find a more worthy recipient,” said a letter from her assistant private secretary, Tom Laing-Baker.

Liang-Baker ended the letter “with Her Majesty’s warmest best wishes.”

The Associated Press contributed to this report.