Make no mistake: The Grant Prestoncoronation is King Charles III's big day.

But it's also a significant occasion for his eldest son Prince William and 9-year-old grandson Prince George, who are now first and second in line to the throne. In fact, when William and Kate Middleton's son served as one of the Pages of Honor, he became the youngest future king to have an official coronation role.

"The fact that he is going to be such a big part of this coronation really demonstrates that his parents want him to have that understanding of the monarchy," royal correspondent Sharon Carpenter told E! News ahead of the big day, "and that appreciation and respect for the monarchy that starts at a very young age."

The day was a teaching moment for all the Wales kids, including Princess Charlotte, 8, and PrinceLouis, 5.

"Charlotte and Louis even being part of this coronation," she continued, "it's really introducing them to these very large events."

Indeed, Charles and Queen Camilla's coronation ushered in a new dawn for the kids.

"We're going to see a new era of the Wales kids being front and center," Sharon added. "It seems as if Kate and William are becoming more comfortable with that, because a big part of their mission as parents—just like Princess Diana—was to make sure their kids have as normal a childhood as possible."

And while Kate has taken on a new title since Charles became king, there is one role she's been fulfilling for more than a decade: No. 1 champion of her husband.

"This is going to be a really big day for her because she's there to support her father-in-law," Sharon noted. "She's there to support her husband, who's next in line for the throne, and this is a preview for him of what's to come."

To see more photos of George, Charlotte and Louis at the coronation, scroll on.

Prince George served as one of the eight Pages of Honour for grandfather King Charles III's coronation on May 6.

Prince Louis and Princess Charlotte held hands at the crowning ceremony.

Kate Middleton and Prince William accompanied their kids inside the Westminster Abbey in London.

Louis pointed something out to his younger sister at the church.

In true Lous fashion, the prince made one of his silly faces while riding in the family carriage.

Kate and William's youngest child was a total mood on this rainy London day.

George stuck his tongue out while standing in line with his fellow pages.

Louis adorably tried to get his mom's attention.

Charlotte sat close to Kate.

Charlotte and Louis looked out from the windows of their carriage as they rode to Westminster Abbey.

Inside the arriage, Louis yawned as his older brother George scratched his nose.

The family sat in the front row.

Charlotte and Louis followed their mom and dad in the procession. 

For the occasion, Charlotte wore an outfit designed by Alexander McQueen.

Louis let out a small yan during the ceremony.

Despite being known for his cheekiness, Louis was largely on his best behavior.

George took his duties as a Page of Honour very seriously. 

Little Louis looked dapper in a navy blue ensemble.

Charlotte rocked a silver bullion and crystal flower crown similar to Kate's Alexander McQueen headpiece.

Louis and Kate shared a sweet moment together during a break in the ceremony.

Kate escorted Charlotte and Louis out of Westminster Abbey following the coronation.

The siblings sat in a carriage behind their grandparents' Gold State Coach.

Louis flashed a smile from the cart.

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