The annual Trooping the Colour event, which celebrates the official birthday of the Sovereign in the United Kingdom, unfolded on Saturday, June 15 this year. Though King Charles III’s actual birthday is on November 14, Trooping the Colour has been the ceremonial celebration of the monarch’s birthday since 1748.

The event is performed annually with a Horse Guards Parade in London, England, by regiments of the Household Division. The event is marked with the King conducting an inspection of his troops. This year, after his diagnosis with cancer, Charles reviewed the troops of his King’s Birthday Parade from an Ascot Landau carriage rather than on horseback, as he did in last year’s celebration

On Friday, Kate Middleton, Princess of Wales, released a personal message, stating she would be attending The King’s Birthday Parade, after all. This marked the Princess’ first public-facing official outing since she attended the Christmas Day 2023 celebrations in Sandringham. Though the royal stated she is “not out of the woods yet,” regarding her own diagnosis of an undisclosed type of cancer following a planned abdominal surgery earlier this year, she said she is making good progress. She is hoping to attend a few other events this summer as well.

Here are 10 surprising facts about the annual Trooping the Colour event.

Trooping the Colour was not always about the Monarch’s birthday

According to The Household Division—the division of the British Army that perform State Ceremonial and public-facing duties, especially in London and Windsor—the ceremony of Trooping the Colour is believed to have been performed first during King Charles II’s reign in the 17th century, when the colors (flags) of the battalion were carried down the ranks so that they could be recognized by all soldiers.

In 1748, it was decided that this parade would be used to mark the official birthday of the Sovereign. Eventually, it became an annual event after George III became King in 1760.

There are two ceremonial rehearsals before the big day

Each year, the full parade is actually conducted three times on consecutive weekends. This year, the first occasion, known as The Major General’s Review, took place on June 1, and the second occasion, The Colonel’s Review, took place on June 8.

In The Major General’s Review, the salute is taken by the Major-General commanding the Household Division. In the Colonel’s Review, the salute is taken by the Royal Colonel of the regiment whose color is being trooped—this year that was the Irish Guards

The Princess of Wales was originally set to salute the Irish Guards (a Foot Guards regiment of the British Army) this year during The Colonel’s Review, but did not attend. Lieutenant General James Bucknall, the former commander of the Allied Rapid Reaction Corps, took her place to perform the salute.

Still, she sent a heartfelt letter to the Irish Guards, wishing them luck on their final rehearsal and apologizing for her absence.

There were certain occasions where Queen Elizabeth II did not take part in the parade

The late Queen Elizabeth II took part in the parade throughout her reign, except for in 1955, when the event was canceled due to a national rail strike, and 2020 and 2021, due to the pandemic. The Queen appeared on the balcony for the event in 2022, but let Charles, then the Prince of Wales, take the parade.

The Queen rode on her favorite horse called Burmese from 1969 until the horse retired in 1986.

In 1981, the Queen had a scare at the annual ceremony 

In 1981, 17-year-old Marcus Serjeant pointed his pistol at the Queen as she rode down in the Horseguards’ Parade, and shot six blanks.

Though Burmese was visibly startled by the shots, the Queen was unharmed. After Serjeant was seized by the police and guardsman, he reportedly said: “I wanted to be famous. I wanted to be somebody.”

King Charles III and Prince William on horseback during Trooping the Colour on June 17, 2023.Neil Mockford—Getty Images

The horses of the Household Cavalry are unique 

The horses in the King’s Birthday Parade are known as the Household Cavalry, and have been taking part in ceremonial occasions since 1660. They are often carefully selected to have good weight, temperament, and presentation.

Each horse is trained for several months at the Household Cavalry Training Wing in Windsor and the Hyde Park Barracks in London, which includes both basic training and riding the horses through the streets to desensitize them to loud noises, cars, and people.

In April, four horses training in the Household Cavalry Mounted Regiment broke loose and bolted across London. The British Army confirmed ahead of Saturday that three of these horses—Tennyson, Trojan and Vanquish—would be taking part in the parade.

The royal family line-up tends to be a talking point

In the past, Trooping the Colour has been a very popular public-facing event for certain members of the royal family as they gather on the Buckingham Palace balcony to watch the parade.

This year, for the second year in a row, Prince Harry and Meghan Markle, the Duke and Duchess of Sussex, were not in attendance.

Much to the delight of the public, the Prince and Princess of Wales attended, alongside Charles and Queen Camilla.

Trooping the Colour is one of the largest military events of the year

The sheer size of the military parade, and the pageantry of it, makes this event unique.

Over 1,400 officers and soldiers form the parade, together with 200 horses; over 400 musicians from ten bands and Corps of Drums march and play in unison, their tunes ringing for all onlookers. The assembled military perform drills to 113 spoken commands. The Household Division’s official site calls it “this impressive display of pageantry.”

In recent years, viewers have been able to watch in-person or online

Trooping the Colour was first broadcast by BBC Radio in 1927 with commentary by Major J. B. S. Bourne-May, a retired officer of the Coldstream Guards.

Now, in-person onlookers hoping to catch a glimpse of the parade can stand on The Mall or on the edge of St James’ Park overlooking Horse Guards Parade.

This year, the leading U.K. network, the BBC, broadcast the event for virtual onlookers. That coverage kicked off at 10:30 a.m. local time, and The Daily Mail’s online portal hosted a livestream on its YouTube channel from 8 a.m.

The whole event can last over two hours

This year, Trooping the Colour officially kicked off at 10:30 a.m., but troops started to gather in London at 10:00 a.m. ahead of the royal family’s departure from Buckingham Palace. The ceremony lasts two-and-a-half hours.

It begins with the King examining the troops, and being greeted by a Royal Salute on Horse Guards Parade and a 41 Gun Salute fired by The King’s Troop Royal Horse Artillery from Green Park.

At the end, the monarch joins their family on the Buckingham Palace balcony, as they all watch a fly-past performed by the Royal Air Force.

There is a dress code for those attending in-person

According to the Household Division, the event is a formal State Ceremonial Parade in the presence of the country’s ruler, and therefore those attending are expected to dress accordingly.

Military personnel are expected to wear their ceremonial attire, but the public are also expected to dress nicely.

The dress code for this year stated: “Morning dress; lounge suit; or jacket, tie & trousers for gentlemen / equivalent for ladies,” specifying no denim, shorts, or sandals.