Cover Queen Elizabeth II, as Princess Elizabeth, and her husband the Duke of Edinburgh, styled Prince Philip in 1957, on their wedding day. (Photo by Hulton Archive/Getty Images)

The Queen and the Duke of Edinburgh mark a historic milestone as they celebrate their 72nd wedding anniversary

Queen Elizabeth, 93, and Prince Philip, 98, marked their 72nd wedding anniversary on Wednesday, having tied the knot on November 20, 1947. The royal couple reportedly spent the day apart, with the Queen occupied with official duties at Buckingham Palace and Prince Philip, having retired from royal duty in August 2017, remained at Sandringham, about 110 miles from London.

To celebrate the special occasion, Prince William and Duchess Kate of Cambridge took to social media to share sweet tributes to the Queen and her husband with a black and white picture of the couple, followed by a more recent photo of the two laughing, while Prince Philip looks at the Queen. 

The caption on the official Kensington Palace Instagram account reads: “Wishing Her Majesty The Queen and His Royal Highness The Duke of Edinburgh a very happy 72nd Wedding Anniversary!”

See also: The Most Expensive Watches Worn By Royalty

Prince Harry and Duchess Meghan of Sussex also gave their special shoutout with a throwback picture of the Queen and the Duke of Edinburgh riding in a royal carriage. “Happy anniversary to Her Majesty The Queen and The Duke of Edinburgh! On this day, seventy-two years ago, they were married at Westminster Abbey, ” the couple wrote in the caption. “Many congratulations!”

Princess Elizabeth and Prince Philip of Greece and Denmark first met at a wedding in 1934. After they met again at the Royal Naval College in Dartmouth in 1939, the year when Philip joined the British Royal Navy, the two began to exchange letters. 

The engagement of the pair was officially announced on July 9, 1947, shortly followed by a grand wedding ceremony which took place on November 20, 1947 at Westminster Abbey—the same place where Prince William and Kate Middleton got married in 2011.

See also: The Most Memorable Royal Engagement Rings, Ranked By Sentimental Value

After the marriage, Elizabeth gave birth to her firstborn, Prince Charles on November 14, 1948, and her only daughter, Princess Anne on August 15, 1950. Her Majesty gave birth to Prince Andrew only a decade after welcoming Princess Anne, followed by her youngest child, Prince Edward.

Together, the couple have lived a lifetime of milestones in their 72 years of marriage—the longest royal marriage in British history. The secret to their longevity is, according to the duke, "tolerance". As he said in a toast to the Queen on their golden anniversary in 1997, "The main lesson that we have learnt is that tolerance is the one essential ingredient of any happy marriage. It may not be quite so important when things are going well, but it is absolutely vital when the going gets difficult."

Netflix responded to the royal anniversary with a tweet, jokingly warn about spoilers for its historical drama series The Crown, which just released its third season last weekend.