73 years ago today, Britain's heir presumptive, Princess Elizabeth, first shared news of her engagement to Lt. Philip Mountbatten, Prince of Greece and Denmark.

The soon-to-be Queen was 21 years old at the time, while her fiancé was 26. They stepped out the following day, July 10, for photographs and to receive congratulations.

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Philip had actually been given permission to marry Elizabeth in 1946, but her father, King George VI, requested that the announcement be delayed until after she turned 21 in April 1947. The young couple was married not too long after the July announcement, tying the knot at their Nov. 20, 1947, royal wedding at Westminster Abbey.

Elizabeth was 5 years away from the throne upon her engagement

The engagement announcement preceded the Princess's accession by five years. Her father, George VI, died in February of 1952, which made Elizabeth the Queen. Philip was also granted the title of the Duke of Edinburgh before their 1947 royal wedding. He was later formally made a British Prince in 1957.

The newly engaged couple is seen below at left, beside the Queen Mother, George VI, and Princess Margaret on July 9, 1947.

Elizabeth and Philip on their engagement day with the Queen Mother, George VI, and Margaret.

Newsreel footage of Elizabeth and Philip's July 10, 1947, engagement event is included below from British Pathé.

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Queen Elizabeth & Prince Philip celebrate 73 years of marriage in 2020

The royal couple will similarly celebrate their 73rd wedding anniversary this November!

The Queen and Duke of Edinburgh at Broadlands, Hampshire.