Princes William, Harry walk together in procession escorting Queen Elizabeth II's coffin

King Charles and his sons are among those joining the procession.

William and Harry, whose father is now the monarch, King Charles III, walked side-by-side in the procession behind Charles and his siblings, Anne, the Princess Royal, and Princes Andrew and Edward.

Catherine and Meghan rode in separate cars behind the procession, with Catherine riding with Camilla, the Queen Consort and Meghan riding with Sophie, the Countess of Wessex.

William and Harry have publicly shown unity in the days since their grandmother's death, despite reportedly having a strained relationship since Harry and Meghan left their senior royal roles in 2020.

William invited the Sussexes to join him and Catherine over the weekend as they viewed tributes to the queen outside of Windsor Castle and to speak with members of the public, a representative for William told ABC News.

The appearance marked the first time the two couples, once called the "Fab Four" by royal watchers, had been seen together in public in over two years.

On Tuesday, Harry and Meghan were among the family members who, along with William and Catherine, privately welcomed the queen's coffin back home to Buckingham Palace for the final time.

On Wednesday, William and Harry together walked the roughly two-mile route from the palace to Westminster Hall, where the coffin will lie in state until the queen's state funeral on Sept. 19 at Westminster Abbey.

Last year, the brothers walked in the same row, separated by their cousin, Peter Phillips, in the procession for their grandfather Prince Philip, who was married to the queen for 73 years at the time of his death.

Watching the brothers walk together behind Philip's coffin brought back memories of a lasting image of William and Harry from 25 years ago.

On Sept. 6, 1997, the two brothers walked behind the coffin of their mother, Princess Diana, on the way to her funeral at Westminster Abbey.

Wednesday's procession for the queen was a personal and somber moment, featuring only a small number of royal family members and members of the military.

The queen's coffin was draped with the Royal Standard. Placed on top of the coffin was the Imperial State Crown on a velvet cushion and a wreath featuring white roses, white dahlias and foliage from Balmoral and Windsor Castles.

Here is a look at the royal family members who joined the procession for the queen

Walking in the procession behind the coffin:

King Charles III, the eldest child of the queen and Philip.

Prince William, grandson of the queen and Philip, and the eldest son of Charles.

Prince Harry, grandson of the queen and Philip, and the younger son of Charles.

Prince Andrew, third eldest child of the queen and Philip.

Prince Edward, fourth and youngest child of the queen and Philip.

Anne, the Princess Royal, the second eldest child of the queen and Philip.

Vice Admiral Sir Tim Laurence, the husband of Princess Anne.

Peter Phillips, the eldest grandchild of the queen and Philip, and the eldest child of Princess Anne and her former husband.

Duke of Gloucester, cousin of the queen.

Earl of Snowdon, nephew of the queen.

Following the procession by car:

Queen Camilla, daughter-in-law of the queen.

Catherine, the Princess of Wales, granddaughter-in-law of the queen.

Meghan, the Duchess of Sussex, granddaughter-in-law of the queen.

Sophie, the Countess of Wessex, daughter-in-law of the queen.