King Charles III's coronation: The biggest moments of the historic event

Royal watchers viewing the coronation will notice three members of Charles’ family missing from today’s festivities.

Harry’s wife, Meghan, the Duchess of Sussex, and their two children, Prince Archie and Princess Lilibet, did not attend the coronation.

Instead, they are home in California, where the family now lives full-time.

Today is Archie’s fourth birthday and Harry is expected to leave shortly after the coronation service to return home to his family.

As a non-working royal, Harry, who sat near his cousins Beatrice and Eugenie inside Westminster Abbey, did not join other members of the royal family in the procession back to Buckingham Palace.

Charles’ grandchildren George, Charlotte and Louis joined the Coronation Procession back to Buckingham Palace, riding in a carriage alongside their parents, William and Kate.

Charlotte, 8, and Louis, 5, sat by the carriage's windows, flanking their older brother George, 9. William and Kate are sitting together across from their children.

Other members of the royal family also traveling by carriage in the procession include Charles’ brother Edward, and his wife Sophie and their two children, Louise and James.

Absent from the procession are Charles’ youngest son, Harry, and his brother, Prince Andrew.

While not present for their coronation, U.S. President Joe Biden offered his congratulations to Charles and Camilla via Twitter.

"Congratulations to King Charles III and Queen Camilla on their Coronation," the president tweeted Saturday. "The enduring friendship between the U.S. and the U.K. is a source of strength for both our peoples. I am proud the First Lady is representing the United States for this historic occasion."

U.S. first lady Jill Biden, who attended the coronation in London, added her own message, tweeting: "The United States and the United Kingdom have a special relationship. It's an honor to represent the United States on this historic day at Westminster Abbey."

Charles selected his only sister, Princess Anne, to lead the procession from Westminster Abbey to Buckingham Palace.

Anne is following right behind Charles and Camilla on horseback as she leads a procession featuring 4,000 personnel, the largest military ceremonial operation of its kind since the queen’s coronation in 1953.