Prince Harry and Prince William Unite for Stunning Vigil at Queen Elizabeth's Coffin with Cousins

Prince Harry and Prince William joined Queen Elizabeth's six other grandchildren for a family vigil.

Harry, 38, William, 40, and their cousins — Peter Phillips, Zara Tindall, Princess Beatrice, Princess Eugenie, Lady Louise Windsor and James, Vicount Severn — gathered on Saturday to host a vigil honoring the late monarch at Westminster Hall ahead of her upcoming state funeral on Monday.

Prince William led the procession in, followed by Prince Harry, both dressed in their Blues and Royals uniforms.

IAN VOGLER/POOL/AFP via Getty Prince William and Prince Harry

Prince William stood at the head of Her Majesty's coffin during the 15-minute vigil, flanked by Princess Anne's two children, Peter, 44, and Zara, 41. Prince Harry took his position at the foot of the coffin alongside Prince Andrew's two daughters, Princess Beatrice, 34, and Princess Eugenie, 32.

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Their other cousins, Lady Louise, 18, and James, 14, stood at the middle of the coffin. Their parents, Prince Edward and Sophie, Countess of Wessex were in Westminster Hall during the ceremony.

RELATED: Princess Anne Makes History as Queen Elizabeth's Children Unite for Vigil Beside Her Coffin

They all stood with their heads bowed with their hands folded in front of them as mourners continued to pass for about 15 minutes, then processed out of Westminster Hall led again by the Prince of Wales.

"The grandchildren, at the King's invitation, are very keen to pay their respects — just as their parents are doing the evening before," a royal source says.

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Aaron Chown/AP/Shutterstock Queen Elizabeth's coffin lies in state

Prince Harry's vigil attire was a departure from previous mourning events honoring the Queen following her death on September 8 at age 96, including Wednesday's procession of her coffin through London, during which he and Prince Andrew both wore morning suits. Buckingham Palace said Monday that during the ceremonial events leading up to and including the Queen's state funeral on September 19, only working members of the royal family who hold military rank will wear military uniforms.

The decision for Prince Harry to wear his military uniform for the vigil was made without him requesting a change, PEOPLE has learned. The Duke of Sussex was prepared to wear whatever was asked. His focus is on honoring his grandmother.

A palace source adds that the wearing of military uniforms at the vigil came "at the King's request."

Chris Jackson/Getty Prince Harry

On Tuesday, Harry's spokesperson told PEOPLE in a statement, "His decade of military service is not determined by the uniform he wears, and we respectfully ask that focus remain on the life and legacy of Her Majesty Queen Elizabeth II."

Prince Harry, who served in the British Army for 10 years and was deployed to Afghanistan twice, lost his three honorary military titles (Captain General of the Royal Marines, Honorary Air Commandant of RAF Honington and Commodore-in-Chief, Small Ships and Diving, Royal Naval Command) after he and wife Meghan Markle stepped back from their senior royal roles in March 2020.

IAN VOGLER/POOL/AFP via Getty James Severn stands vigil for Queen Elizabeth

Queen Elizabeth's four children — King Charles III, Princess Anne, Prince Andrew, and Prince Edward — united twice in the past week to hold a vigil around their mother's coffin for a symbolic stand of guard.

Known as the Vigil of the Princes, Princess Anne made history by being the first female royal family member to participate in the event.

HANNAH MCKAY/POOL/AFP via Getty King Charles

Saturday's vigil comes three days after Peter, Zara, William, Harry, Beatrice, Eugenie, Louise and James attended a service honoring their grandmother at Westminster Hall.

In one photo, Eugenie could be seen wiping away tears as she stood with family members. She was joined by her husband, Jack Brooksbank. Beatrice's husband, Edoardo Mapelli Mozzi, and Zara's husband, Mike Tindall, were also present.

Chris Jackson/Getty

The service came after the coffin of the late Queen, who died at Balmoral Castle in Scotland last Thursday, traveled from Buckingham Palace to Westminster Hall on Wednesday in a solemn procession.

RELATED VIDEO: Prince Harry and Prince William Unite for Stunning Vigil at Queen Elizabeth's Coffin with Cousins

The procession included her four children and several of her grandchildren, including Peter, William and Harry, with the latter two walking side-by-side.

Also taking part were Princess Anne's husband Sir Timothy Laurence, the Queen's cousin Prince Richard the Duke of Gloucester and the Queen's nephew David Armstrong-Jones, the Earl of Snowdon. Members of the Queen's staff also participated in the procession.