Trooping the Colour is looking very different this year.

King Charles III and his daughter-in-law Kate Middleton, the Princess of Wales, made a grand appearance at the public celebration despite their health battles.

Saturday’s festivities mark Kate’s first public appearance since announcing her cancer diagnosis in March. It’s also the 42-year-old’s first official outing since Christmas.

TRY FOX NEWS’ FUN NEW GAMES PAGE, WITH 6 GAMES TO CHOOSE FROM!

An eager crowd snapped pictures of the princess with their mobile phones when she made her first appearance at The Mall, a ceremonial roadway in the City of Westminster, in the heart of London. She is wearing white with navy details.

Catherine rode in the Glass Stage Coach with her children, Princess Charlotte, Prince George and Prince Louis, and will later appear on the Buckingham Palace balcony. 

She is the honorary colonel of the Irish Guards, which is presenting its flag in the parade. 

This year also marks the king’s second Trooping the Colour as monarch following the death of his mother, Queen Elizabeth II, in 2022. Charles, 75, is being treated for an undisclosed form of cancer.

KATE MIDDLETON TO MAKE FIRST PUBLIC APPEARANCE SINCE CANCER DIAGNOSIS, SAYS CHEMO TREATMENT WILL CONTINUE

Trooping the Colour takes place in June each year to celebrate the monarch’s birthday, regardless of when their actual birthday is. The annual event highlights the ceremonial presentation of the military’s flags or “colours.”

“The very first Trooping the Colour, ironically, was instigated by King Charles II in the 1600s,” Christopher Andersen, author of “The King,” told Fox News Digital.

“But it wasn’t until Edward VII inherited the throne from his mother, Queen Victoria, in 1901 that they moved the date,” Andersen explained. “King Charles III’s birthday is November… Well, King Edward’s birthday was also in November, and he didn’t like the weather then. So he said, ‘It’s much nicer to have a parade in June.’ And so, they moved the day to either the first week, the first Saturday in June, or the second Saturday in June. And it’s been that way ever since.”

CLICK HERE TO SIGN UP FOR THE ENTERTAINMENT NEWSLETTER

“The queen used this [day] as a way to connect with her people,” Andersen continued. “… She never missed one. She only missed one Trooping the Colour during her entire 70-year reign. And that was in 1955 because it was canceled. The entire event was canceled due to a rail strike… She showed up every single time that she could.”

According to the royal family’s website, over 14000 parading soldiers, 200 horses and 400 musicians come together to mark the sovereign’s birthday. The parade highlights the royal family on horseback and in carriages.

Charles was seen seated in a horse-drawn carriage alongside Queen Camilla. The king saluted as he rode along, visible to the crowd through glass windows. 

For the ceremony, the king wore the tunic of the Guard of Honour Order with a blue garter sash, to honor the Irish Guard regiment. 

During last year’s Trooping the Colour, Charles was on horseback alongside Prince William and Prince Edward. 

“People may remember that in 1981, while [the queen] was on her horse and her uniform, a person who, at the time was slightly unhinged, fired off blanks… near the horse,” said Andersen. “The horse bolted in front of everybody in the middle of the parade. She managed to get control of the horse. It was a wonderful moment for the monarchy because it showed that she was still very much in control.”

LIKE WHAT YOU’RE READING? CLICK HERE FOR MORE ENTERTAINMENT NEWS

“… I remember attending her Silver Jubilee in 1977,” said Andersen. “It was her 25th anniversary on the throne. She was constantly photographed on horseback.”

The king, as well as his heir and Princess Anne, will likely have their military uniforms on display. But for the royal women, including Queen Camilla, the Princess of Wales, Princess Beatrice and Princess Eugenie, they will showcase their royal fashion with stylish, head-turning hats.

The Prince and Princess of Wales’s three children – Prince George, Princess Charlotte and Prince Louis – have made their mark in previous years with adorable moments on the palace balcony. Other royals who may appear on the palace balcony include Sophie, Duchess of Edinburgh, as well as the Duke of Kent and the Duke and Duchess of Gloucester.

Prince Harry and Meghan Markle were not invited to Trooping the Colour for the second year in a row. The Duke and Duchess of Sussex stepped back as senior royals in 2020 and moved to California.

It’s unclear if Prince Andrew will appear at Trooping the Colour. The Duke of York announced he was stepping back as a senior royal in 2019 following his relationship with late financier and convicted sex offender Jeffrey Epstein.

According to the palace, the king will arrive at the Horse Guard’s Parade in Whitehouse. He will be greeted with a royal salute before inspecting the troops. After the military bands perform, the escorted Regimental Colour, or flag, is processed down the ranks of soldiers. Over 100 words of command are used by the Officer in Command of the Parade to direct hundreds of soldiers.

The palace noted that once the Foot Guards march past the sovereign, they ride back to Buckingham Palace at the head of the soldiers before taking the salute again. The king then joins other members of the royal family on the balcony of Buckingham Palace to watch a fly-past by the Royal Air Force. The event concludes with a 41-gun salute fired in Green Park.