The Sussexes and Cambridges joined the Queen for this year's Festival of Remembrance at the Royal Albert Hall.
The Prime Minister was also among those gathered to pay tribute to all those who lost their lives in conflicts.
Royal couples the Duke and Duchess of Cambridge and the Duke and Duchess of Sussex sat with the Queen in the royal box at the event.
It is the first time the Sussexes and Cambridges have appeared in public together since Harry and Meghan opened up about their struggles in an emotional television documentary.
Also alongside the Queen in the royal box at the Royal Albert Hall were senior royals including the Prince of Wales and the Duchess of Cornwall, who earlier this week was forced to pull out of engagements because of ill health.
The service at the Royal Albert Hall was also attended by the Duke of York, the Earl and Countess of Wessex, the Princess Royal, the Duke and Duchess of Gloucester, the Duke of Kent and Vice Admiral Sir Tim Laurence.
The mood fell sombre when The Last Post rang out in the theatre, and during the minutes of silence poppy petals drifted from the ceiling.
It concluded with traditional prayers, hymns and blessings before an enthusiastic rendition of God Save the Queen.
The Queen waved to the crowd before leaving.
Musical performances were led by Jeff Goldblum, James Blunt, Louise Dearman and Colin Thackeray.
This year's event marked 75 years since notable battles of 1944 including Monte Cassino, Kohima and Imphal, D-Day and the collaboration of Commonwealth and Allied forces.
It celebrated the 100th anniversary of the Government Communications Headquarters and pay tribute to RFA Mounts Bay which delivered supplies and aid to the Bahamas after Hurricane Dorian this year.
The ceremony was hosted by the Royal British Legion and commemorates all those who lost their lives in conflicts.