The Archbishop of Canterbury and members of the royal family gathered at Westminster Abbey to remember Britain's fallen heroes.
The socially distanced service marked the 100th anniversary of the Unknown Warrior's burial at the abbey, and took place as the nation joined in a two-minute silence to remember its war dead.
Archbishop Justin Welby remembered the millions who have gave up their lives in war for the sake of the nation, but also paid tribute to the "glorious" sacrifice of many people during the coronavirus pandemic.
"We pay tribute to the many millions of men and women who have died on so many battlefields, unnamed and unclaimed except by God," he said.
"Sacrifice is not only in time of war. In war and peace, sacrifice is the virtue that smooths the rough roads over which our societies travel.
"This year sacrifices have been made and are being made by thousands, even millions unknown. People have put aside all they hold dear. We may never meet them, or read their names. We might not know what they have suffered or given up. They may be anonymous, but their actions are glorious."
The intimate service was joined by Prince Charles and the Duchess of Cornwall, as well as Prime Minister Boris Johnson and opposition leader Sir Keir Starmer.
The body of the unknown British serviceman was brought back from northern France and buried in 1920 as a symbol of all the fallen in the war who were never identified or whose bodies were never recovered.
People across the country observed a two-minute silence in their homes and on doorsteps, while veterans turned out for scaled-back ceremonies at war memorials.