Princess of Wales joins Royal Family at annual Trooping the Colour event

According to CNN, the princess arrived at Buckingham Palace in a car alongside Prince William and their three children, princes George and Louis and Princess Charlotte. She was later seen waving from a carriage as she and the children were driven from Buckingham Palace to Horse Guards Parade to watch the celebration.

Prince William took part in the festivities from horseback, Time magazine reported.

King Charles III, who announced his own cancer diagnosis in February, and Queen Camilla were also taken to the event by carriage. While the king would ordinarily be on horseback for the ceremony, he chose this year to inspect the troops on foot.

Trooping the Colour is a military event that, for more than 260 years, has marked the official birthday of the sovereign, CNN reported. Charles was actually born in November.

The annual celebration includes 1,400 officers and soldiers, 400 musicians and 200 horses in a parade that winds through the London streets from the palace to Horse Guards Parade.

According to the Royal Parks website, Horse Guards is the official entrance to St. James’ and Buckingham Palace. Each year during the Trooping the Colour event, the central windows of the building are opened so the Royal Family can watch as the king or queen inspects the troops below.

On Friday, Kate released an update on her health in which she said she is “making good progress” but that she is “not out of the woods yet.”

“My treatment is ongoing and will be for a few more months,” the statement read. “On the days I feel well enough, it is a joy to engage with school life, spend personal time on the things that give me energy and positivity, as well as starting to do a little work from home.”

Kate announced earlier this year that she was diagnosed with an undisclosed type of cancer following abdominal surgery in January, Time reported. She has been undergoing a course of preventative chemotherapy to keep the disease at bay.