Kate Middleton's reappearance could save the royal family

• Kate Middleton attended the King's Parade, marking her first engagement since her cancer diagnosis.
• In a statement on Instagram, Kate said she hoped to attend more events over the summer.

Kate Middleton attended King Charles III's birthday parade this weekend — her first royal engagement since she announced her cancer diagnosis in March.

In a statement shared to Instagram on Friday, Kate said her cancer treatment was ongoing and likely to last "for a few more months," though she hoped to join more engagements over the summer.

"I'm looking forward to attending The King's Birthday Parade this weekend with my family and hope to join a few public engagements over the summer, but equally knowing I am not out of the woods yet," Kate said.

The princess's tentative return to royal duties comes after a difficult period for the royal family, which included the "Katespiracy" theories and the slimmed-down monarchy seemingly threatening the family's future.

Kate's return signals a 'show of unity'

Kate's return was every bit as glamorous as you may expect.

The royal, wearing a white and black Jenny Packham dress and matching fascinator, traveled in a carriage before greeting the crowds from the Buckingham Palace balcony with Prince William, King Charles, Queen Camilla, and the children.

Richard Fitzwilliams, a royal commentator, told Business Insider that Kate's appearance was "a timely and extremely beneficial show of unity for the monarchy after a very difficult few months."

Photos from the event show Kate standing next to her father-in-law, Charles, who spoke about his experience with cancer earlier this year. Fitzwilliams said the pair's decision to stand together was probably intentional as a "courageous and mutually supportive gesture."

"The images will go worldwide and will be extremely positive and be beneficial for the institution," he said. "The late Queen used to say, 'I must be seen to be believed,' and it was most important that we saw Catherine on this occasion."

Kate's return comes after a period of uncertainty over the monarchy's future. Royal commentators previously told BI that cracks in the king's slimmed-down monarchy were on show following Charles and Kate's absences.

The royal biographer Phil Dampier said the monarchy "could, with the wrong unforeseen circumstances, collapse quite quickly" if something were to happen to both the king and Prince William, who's first in line to the throne.

The royal family carried out a collective 4,000 engagements in 2014, including Prince Harry's trip to Brazil and the Queen and the Duke of Edinburgh's engagements in France and Italy. The Guardian reported that this year, the family was expected to carry out "little more than half" of the engagements it did a decade ago.

A source of reassurance

Earlier this year, the family also had to deal with swirling conspiracy theories about Kate's whereabouts during her absence from public duties. The speculation came to a head after Kate apologized for an edited Mother's Day photo that had been recalled by major photo agencies over concerns it had been manipulated.

Jack Royston, a royal commentator and podcast host, told BI that any lurking conspiracy theories would have been "blown out of the water" by Kate's return.

"And for the public, the message will be that they can stop worrying about Kate," Royston said. "She's made it clear she isn't completely out of the woods or back at work full time, but we may well see her again over the summer."

Robert Hardman, the author of "Charles III: New King. New Court. The Inside Story," told BI that seeing Kate in public would be a source of reassurance amid uncertain times.

"Her presence has shown how big her absence is. When she wasn't around, everyone was worried," Hardman said. "The royal family has a strange position in our society, where everyone, to an extent, feels like it's an extension of our own families."

"It will have cheered people up to see Catherine with her children playing an enthusiastic, central part of one of the year's biggest events," he said.

"It's a sign of her dedication to the institution."

Buckingham Palace and Kensington Palace didn't immediately respond to requests for comment.