King Charles’ soldiers are honoring the victims of 9/11 on the 25th anniversary of the attack.

On Friday, Sept. 11, the British Army’s Band of the Coldstream Guards performed songs including John Philip Sousa’s “The Thunderer” and “The Stars and Stripes Forever” as they marched to Buckingham Palace.

The commemorative Guard Change on the forecourt also included performances of both U.S. and U.K. national anthems, as well as “Hymn to the Fallen” from Saving Private Ryan and “Amazing Grace.”

Prince Richard, the Duke of Gloucester, and Birgitte, the Duchess of Gloucester, attended Friday’s performance on behalf of King Charles, taking the salute on the palace’s forecourt alongside U.S. Ambassador to the U.K. Warren Stephens.

British and American nationals were among approximately 40 invited guests at the ceremony.

The performance comes after Queen Elizabeth requested that the Band of the Coldstream Guards perform the U.S. national anthem during the Changing of the Guard on  Sept. 13, 2001 — two days after the terrorist attack occurred in New York City.

Friday marked 25 years since members of the al-Qaeda terrorist group hijacked four planes, flying two into New York City’s World Trade Center buildings, one into the Pentagon and another into a Pennsylvania field after passengers tried to take back control of the aircraft.

9/11 remains the deadliest terror attack on U.S. soil, with 2,977 people killed, and thousands of people who worked, lived, or went to school near Ground Zero still struggling with lingering, debilitating illness.

In April of this year, King Charles and Queen Camilla visited the National September 11 Memorial & Museum in New York City, laying a bouquet of white flowers at the edge of the south reflecting pool to honor the lives lost, which included 67 British victims.

The King and Queen attended the brief ceremony to commemorate the 25th anniversary since the attack, marking their first visit to the memorial, which opened in 2011. They were joined at the time by former New York City Mayor Michael Bloomberg.

During the visit, the royal couple also met families of victims and first responders who were involved in the rescue efforts after the attacks, as well as currently serving personnel and some of the charities that support families of victims.

The palace previously confirmed a handwritten card attached to the flowers they laid at the site read, “We honour the memory of all those who so tragically lost their lives on 11th September 2001, and stand in enduring solidarity with the American people in the face of such profound loss.”

The note was signed from “Charles R” and “Camilla R,” using the traditional signature for the sovereign and his spouse, with the “R” standing for “Rex” and “Regina,” the Latin words for “king” and “queen.”