Thousands in central London paused for a moment's reflection Sunday to remember all those who have fallen in combat, as Queen Elizabeth II led Britain's annual Remembrance Day service.

To the chimes of Big Ben at 11 a.m., veterans, servicemen and thousands of others gathered in Whitehall bowed their heads for a two-minute silence.

The moment was broken by the sounding of "The Last Post," the traditional trumpet call commemorating the war dead, and the queen laid the first wreath at the foot of central London's Cenotaph war memorial.

The solemn ceremony takes place every year on the 11th hour on the nearest Sunday to the anniversary of the end of World War I on Nov. 11, 1918. The day now also pays tribute to the dead in all conflicts, including World War II, Iraq and Afghanistan.

Smaller services also took place across Britain, in Commonwealth countries, and in southern Afghanistan, where British troops have been fighting the Taliban for more than a decade.

On a visit to Afghanistan, Prince Andrew and Defence Secretary Philip Hammond each laid a wreath at a memorial in Camp Bastion in front of soldiers gathered for the tribute.

"We are not just remembering the millions of people who gave their lives in the two world wars but all those who have since died in the service of our country," Hammond said.

In London, the Queen was joined by her husband, Prince Philip, and her grandsons, Princes William and Harry, who also laid wreaths of red poppies at the Cenotaph. William's wife, Kate, the Duchess of Cambridge, watched from a nearby balcony.

The War Widows Association, wearing black coats and red scarves, headed a march down Whitehall to mark the loss of those departed. They were followed by a parade of around 10,000 veterans — some in wheelchairs — as well-wishers lining the streets cheered.

Politicians including Prime Minister David Cameron and his predecessors John Major, Tony Blair and Gordon Brown also attended the ceremony.