Queen Elizabeth II, the world's longest serving monarch, has died at the age of 96. She passed "peacefully" at Balmoral Castle in Scotland, the British royal family said in a statement.

Elizabeth's seven-decade regin oversaw a rapidly changed world past World War II as Britain's once-global empire declined and the role of a monarch in the modern age evolved. Under the plan "Operation London Bridge," her death commences 10 days of national mourning.

Upon her death, her son Charles became the the 62nd British monarch and will be called King Charles III, ruling over England and 14 other Commonwealth nations. The 73-year-old is the oldest person to ever assume the throne.

Appearing outside of 10 Downing Street, newly appointed Prime Minister Liz Truss confirmed the British monarch as the new head of state.

"Today, the crown passes, as it has done for more than 1,000 years to our new monarch, his majesty King Charles III," Truss said in a statement.

Born April 21, 1926, Elizabeth was the first child of the Duke and Duchess of York, who later become King George VI and Queen Elizabeth right before the start of WWII in 1937.

During the war, she made her first radio broadcast in 1940 at age 12, addressing children who had fled from their homes to avoid the bombing of British cities by Germany. Later on, Elizabeth served as a driver for the Auxiliary Territorial Service.

Elizabeth became queen of the United Kingdom, Canada, Australia and New Zealand upon the death of King George VI on Feb.6, 1952, with her coronation later on June 2, 1953. As queen, Elizabeth oversaw the transition of the global British Empire into a Commonwealth of 52 independent nations, as well as the nation's entrance and exit from the European Union.

She celebrated six jubilees, her 25th, 40th, 50th, 60th, and the country's first 70th, or Platinum Jubilee in June 2022. In 2015, Elizabeth overtook her great-great-grandmother Queen Victoria to become the oldest and longest-reigning British monarch.

During her long time on the throne, Elizabeth ruled over fifteen prime ministers--from Winston Churchill to now Liz Truss. She had met with every United States president from Harry Truman to Joe Biden, expect for Lyndon B. Johnson. She was also visited the White House to be hosted by five presidents--Dwight Eisenhower, Gerald Ford, Ronald Reagan, George H. W. Bush and George W. Bush.