Queen Elizabeth II, the longest-reigning monarch in British history, dies at age 96

With the passing of the queen, Charles, Prince of Wales, the eldest of her four children and the oldest heir apparent in British history at 73, will automatically take over as king immediately to the throne.

Her son King Charles III said the passing of his beloved mother was a "moment of great sadness" for him and his family and that her loss will be "deeply felt" all around the world.

More specifically, he added, "We mourn profoundly the passing of a cherished sovereign and a much-loved mother.

Following the passing of Queen Elizabeth II in Balmoral, Scotland, the British government has begun "Operation Unicorn."

In order to control events during the first 10 days between the Queen's passing and the funeral, UK officials devised Operation London Bridge.

The day after Thursday has been declared as "D-Day," and the days that follow are "D 1" and "D 2" until the tenth of her passing.

As per one official memo, the phrase "London Bridge is down" is the code for conveying the Queen's death.

The report stated that a massive security operation to control crowds and traffic chaos would then take place.

At Westminster Abbey, there will be a state funeral, and at Windsor Castle's St. George's Chapel, there will be a committal service.

In the King George VI Memorial Chapel of the castle, Queen Elizabeth II will then be given her final rest.

The Queen was born at 17 Bruton Street in Mayfair, London, on April 21, 1926. She was The Duke and Duchess of York's first child, who eventually became King George VI, and Queen Elizabeth.