The UK’s Head of State Queen Elizabeth is the longest-reigning monarch in Britain's history

On Sunday, February 6, Queen Elizabeth II will become the latest monarch to reign for 70 years, a milestone never reached by any of her predecessors over the last 1,000 years.

Elizabeth, 95, became the queen of Britain and more than a dozen other realms including Canada, Australia and New Zealand on the death of her father King George VI on February 6, 1952, while she was in Kenya on an international tour.

The news was broken to her by her husband Prince Philip, who died last year aged 99 after more than seven decades by her side.

Elizabeth will mark 'Accession Day' in private as is customary, not viewing it as something to celebrate. But there will be four days of national events to mark her Platinum Jubilee in June.

"While it is a moment for national celebration, it will be a day of mixed emotions for Her Majesty as the day also marks 70 years since the death of her beloved father George VI," United Kingdom Prime Minister Boris Johnson told parliament on Wednesday.

Britain's Queen Elizabeth II looks at a display of memorabilia from her Golden and Platinum Jubilees in the Oak Room at Windsor Castle, Windsor, England, Feb. 4. Queen Elizabeth II will mark 70 years on the throne Feb. 6, an unprecedented reign that has made her a symbol of stability as the United Kingdom navigated an age of uncertainty. AP-Yonhap Pulse Live Kenya

How Elizabeth became Queen

On the morning of her father’s death, 25-year-old Elizabeth was perched in the Treetops hotel in Nyeri, from which she’d watched a herd of elephants come to a watering hole.

Back in the UK, the ailing King George VI died in the early hours of the morning at Sandringham. Without ceremony or even awareness, but in accordance with British tradition, Elizabeth had become queen.

The British newspaper front pages rang out, “Long Live Queen Elizabeth,” while noting, “Her Majesty, pale with grief, leaves by air for home.”

Queen Elizabeth II and Prince Philip, Duke of Edinburgh during a visit to the first President of Kenya, Jomo Kenyatta, Kenya, 1972. (Photo by William Lovelace/Daily Express/Hulton Archive/Getty Images) Pulse Live Kenya

There was a proclamation of the accession at St. James’s Palace in London that day, signed by 150 members of the Privy Council.

More than a year later, on June 2, 1953, the over-the-top coronation of Elizabeth II took place in Westminster Abbey, a much more joyous, public, televised occasion, watched by millions.