World War One in numbersPublished5 November 2018Image source, Getty ImagesImage caption, World War One started in 1914 and ended in 1918.Image source, PAImage caption, Britain's entry into World War One was announced at 11pm on 4 August 1914.Image source, Getty Images (Source: Imperial War Musuem)Image caption, 65 million people around the world fought in the war. Around five million of those were British.Image caption, Officially, you had to be 18 to sign up to the armed forces and 19 to serve abroad. However, the youngest British soldier was a 12-year-old who lied about his age.Image source, Source: Imperial War MuseumImage caption, 8.5 million troops are thought to have been killed, including around 750,000 British servicemen.Image source, Getty Images (Source: Imperial War Museum)Image caption, 21 million troops were wounded, of whom around 1.5 million were British.Image source, Getty ImagesImage caption, 12 million letters were delivered to the front every week. By the end of the war, two billion letters and 114 million parcels had been delivered.Image source, Source: Imperial War MuseumImage caption, An estimated two million soldiers, sailors and airmen died from disease, malnutrition and other causes.Image source, Getty Images Source: Imperial War MuseumImage caption, An estimated 13 million civilians were also killed.