On the 7th of August, 1914 the first British troops - 120,000 highly trained members of the regular Army formed the British Expeditionary Force (BEF) commanded by Field Marshal John French - landed in France. They had been deployed in response to the German invasion of Belgium which violated the Treaty of London (1839) and forced the British to declare war on Germany - the most destructive and deadliest conflict the world had ever seen. The chain of events that led to World War I was not immediately obvious to the average person on the streets--in the days before television, rolling news or the use of radio as an entertainment and communication medium there was only one way for people to hear about what was happening, from reading the daily papers. Through the remarkable Daily Mirror archive, we reveal the key factors in the outbreak of the Great War in a way that brings the era to life and reveals much that has been lost to the mists of time.