How King Charles Will Make History When He's Proclaimed Monarch on Saturday

Preparations begin to usher in King Charles III.

The 73-year-old royal will be formally proclaimed King by the Accession Council on Saturday morning — and in a historic first, the rite will be televised. The decree will be made in the State Apartments of St. James' Palace in London at 10 a.m. local time, Buckingham Palace said in a statement Friday.

Though he immediately rose in rank after mother Queen Elizabeth's death, the accession is not to be confused with the formal coronation. The first step of several formalities, tomorrow marks the meeting of the Accession Council, comprised of officials from the Privy Council, including senior Cabinet ministers, judges and leaders of the Church of England, the Associated Press reports.

At the gathering, Charles will be formally proclaimed the new sovereign. In royal transitions past, this ritual occurred behind closed doors, making tomorrow's broadcast all the more momentous.

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The new monarch will also swear an oath before the Privy Council to preserve the Church of Scotland. This will be followed by the public proclamation of the new sovereign, read publicly at St James' Palace and at various locations through Edinburgh, Scotland, Cardiff, Wales, and Belfast, Ireland.

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Hugo Burnand-Pool/Getty King Charles III

Charles' formal coronation is not immediately expected, and courtiers have not announced a date. The crowning ceremony for his mother was held 16 months after her accession on Feb. 6, 1952, following the sudden death of her father, King George VI.

In updated communications on Buckingham Palace's website, King Charles has asked the public to observe a period of mourning, effective immediately and lasting until one week after Queen Elizabeth's funeral, the date of which has not yet been announced.

"Following the death of Her Majesty The Queen, it is His Majesty The King's wish that a period of Royal Mourning be observed from now until seven days after The Queen's Funeral," a statement says. "The date of the Funeral will be confirmed in due course."

Aaron Chown/AFP/Getty Queen Elizabeth and Prince Charles

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Flags will be flown at half-staff at royal residences through the period, and the buildings themselves will be closed.

Though there are no formal condolence books, supporters are invited to share sympathies on the royal website.