World War One Anniversary: PICS

People observe a moment of silence near a war memorial in Westminster during "Lights Out", as part of commemorations to mark the 100th anniversary of the outbreak of World War One, in London August 4, 2014. Lights across Britain switched off for an hour on Monday night in a tribute to the dead of World War One inspired by the prophetic observation of Britain's foreign minister on the eve of war 100 years ago. REUTERS/Dylan Martinez (BRITAIN - Tags: POLITICS ANNIVERSARY CONFLICT)

People enjoy an artwork entitled "Spectra" by Japanese visual artist Ryoji Ikeda during "Lights Out", as part of commemorations to mark the 100th anniversary of the outbreak of World War One (WWI), in London August 4, 2014. Lights across Britain were being switched off for an hour on Monday night in a tribute to the dead of World War One, inspired by the prophetic observation of Britain's foreign minister on the eve of war 100 years ago. Spectra's illuminations will light up the London skyline for seven nights. REUTERS/Dylan Martinez (BRITAIN - Tags: POLITICS ANNIVERSARY CONFLICT TPX IMAGES OF THE DAY)

A message on a wreath laid by Britain's Prime Minister David Cameron is seen at the Cenotaph, following a ceremony to commemorate the 100th anniversary of the outbreak of World War One (WW1), in Glasgow, Scotland August 4, 2014. REUTERS/Danny Lawson/Pool (BRITAIN - Tags: SOCIETY ANNIVERSARY CONFLICT POLITICS MILITARY)

Some 600 balloons emblazoned with a poppy and the name of a fallen soldier flutter in the sky during the "Short Step" ceremony, to mark the 100th anniversary of the outbreak of World War One (WW1), in Folkestone, southern England August 4, 2014. REUTERS/Dylan Martinez (BRITAIN - Tags: POLITICS ANNIVERSARY CONFLICT TPX IMAGES OF THE DAY)

People enjoy an artwork entitled "Spectra" by Ryoji Ikeda during "Lights Out", as part of commemorations to mark the 100th anniversary of the outbreak of World War One, in London August 4, 2014. Spectra's illuminations will light up the London skyline for seven nights. REUTERS/Dylan Martinez (BRITAIN - Tags: POLITICS ANNIVERSARY CONFLICT)

Camilla, Duchess of Cornwall, second left, extinguishes the remaining flame at the Grave of the Unknown Warrior during a candlelit vigil and prayer service to commemorate the centenary of the outbreak of the First World War at Westminster Abbey in London, Monday, Aug. 4, 2014. (AP Photo/Sang Tan, Pool)