Pope Francis sent a congratulatory message to Queen Elizabeth II on Thursday coinciding with the United Kingdom's joyous celebration of the 70th anniversary of her reign.

"On this joyful occasion of your Majesty's birthday, and as you celebrate this Platinum Jubilee year, I send cordial greetings and good wishes, together with the renewed assurance of my prayers that Almighty God will bestow upon you, the members of the Royal Family and all the people of the nation blessings of unity, prosperity and peace," the pope said in a telegram to the queen.

Queen Elizabeth, who turned 96 on April 21, is England's longest serving monarch, having ascended to the throne in 1952 at age 25 after the death of her father, King George VI. Her coronation took place the following year.

On Thursday the United Kingdom began four days of jubilee celebrations, starting with an event called Trooping the Color, a colorful military parade in London that featured 240 horses, a Royal Air Force flyover, and a gun salute. The queen watched the parade from a balcony at Buckingham Palace.

Elizabeth has met four popes as queen, and one (Pius XII) as princess in 1951.

Queen Elizabeth and her late husband, Prince Philip, the Duke of Edinburgh, met with Pope Francis in the Vatican in 2014.

The meeting marked the 100th anniversary of the re-establishment of diplomatic relations between the United Kingdom and the Holy See.After their meeting, Pope Francis gave the couple a facsimile of Pope Innocent XI's order extending the cult of St. Edward the Confessor, and the queen in turn presented the pope with a large basket of food from the estates surrounding her homes. The items included an assortment of honey, a dozen eggs, a haunch of venison, shortbread, juice, preserves, and Balmoral whiskey.