Britain's most famous landmarks including the London Eye, Houses of Parliament, Downing Street and Gateshead's Millennium Bridge were plunged into darkness for an hour last night to mark the moment Britain first declared war on Germany in 1914.
War must always represent the abject failure of humanity, the head of the Anglican church in Ireland has said.
Archbishop of Armagh Dr Richard Clarke said commemorating the First World War could not be spiritually separated from the situation in Gaza and other recent conflicts.
Dr Clarke said: "War must always represent the abject failure of the human spirit and of humanity itself.
"It can never be other and we should never pretend it is other."
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.