The UK's King Charles III marks his first official birthday celebrations as monarch on Saturday with the prestigious Trooping the Colour ceremony, also known as the King's Birthday Parade.
The tradition of the annual military parade goes back to almost three centuries — and has become a staple of the British cultural calendar. The history of the parade is intertwined with that of the Brits military.
The word "colours" refers to a term historically used to describe the regimental flags of the British Army. It was important that these flags were clear and bright because they acted as a rallying point in battle.
But in order for soldiers — or troops — to recognize these "colours," they had to be displayed regularly before battle. This process became known as "trooping," hence the name of the ceremony.
The specific ceremony of the regiment of the King's Guards is believed to have first been performed in the 17th century during the reign of Charles II. But it was not until 1748 when it was decided that this parade would be used to mark the official birthday of the sovereign, under George II.
Here are five things to watch out for at the 2023 ceremony.
Monarch rides a horse
King Charles, 74, will ride horseback with his soldiers, reviving a tradition that his mother, Queen Elizabeth II, gave up in 1986. The then 60-year-old sovereign decided she would rather be driven in a carriage from then on as her preferred horse, Burmese, had been retired from duty.
Last year's Trooping the Colour was one of the final public appearances by the 96-year-old queen, whose Platinum Jubilee, marking 70 years on the throne, was celebrated at the same time with a public holiday. Queen Elizabeth II died in September.
Parade in the heart of London
The parade begins at Buckingham Palace in central London and moves down the Mall — the boulevard in front of the palace — to Horse Guards Parade. There, the king will receive a royal salute. He will then inspect the soldiers on parade.
Over 1,400 officers are on display, with 200 horses and 400 musicians. The event on June 17 was preceded by two rehearsals of similar scale, overseen by senior military figures, without the monarch present.
Eyes on the sky
One of the most visually stunning parts of the ceremony is the military flypast by the famed Red Arrows, the aerobatics team of the British Royal Air Force. The king and members of his family will watch from the balcony on Buckingham Palace.
The flypast scheduled for the king's coronation was shortened and simplified because of poor weather.
The whole family … mostly
Charles' son, Prince William, is in attendance, along with Charles' equestrian sister Princess Anne and several other members of the family. Notably absent are Prince Harry and his wife Meghan, who moved to the United States in 2020, having retired from their royal duties.
In May, Harry attended his father's coronation without Meghan or his children. Reportedly, none of them received an invitation to this ceremony.
Soaring temperatures of 28 degrees Celsius (82 Fahrenheit) in the UK saw several soldiers faint at one of the rehearsals earlier in the month, overseen by Prince William. Officials will be hoping that nothing of the kind will happen this Saturday.
The reason the event takes place at this time of year is to make the most of the good weather. German-born monarch George II was the first to introduce the second summer birthday in 1748; his real birthday was October 30. Charles' actual birthday is November 14, and the palace has confirmed that the official birthday will be celebrated on the third Saturday in June for the duration of his reign.