French President Francois Hollande joined Belgium's King Philippe and Queen Mathilde in Liege to watch an air force flypast to commemorate the centenary of the First World War.
Germany invaded neutral Belgium on 4 August, 1914, as part of a planned attack on France.
By nightfall, Britain had declared war on Germany and joined the conflict.
As the Lights Out event to remember those who fought and died in WWI happened last night ITV asked our viewers what they did to take part.
Lights on some of Britain's most famous landmarks were extinguished between 10pm and 11pm to remember those who died in WWI.