World War I (WWI or WW1 or World War One); also known as the First World War or the Great War; was a global war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918. More than 9 million combatants and 7 million civilians died as a result of the war; a casualty rate exacerbated by the belligerents' technological and industrial sophistication; and tactical stalemate. It was one of the deadliest conflicts in history; paving the way for major political changes; including revolutions in many of the nations involved.

The war drew in all the world's economic great powers; which were assembled in two opposing alliances: the Allies (based on the Triple Entente of the United Kingdom; France and the Russian Empire) and the Central Powers of Germany and Austria-Hungary. Although Italy had also been a member of the Triple Alliance alongside Germany and Austria-Hungary; it did not join the Central Powers; as Austria-Hungary had taken the offensive against the terms of the alliance.

These alliances were reorganised and expanded as more nations entered the war: Italy; Japan and the United States joined the Allies; and the Ottoman Empire and Bulgaria the Central Powers. Ultimately; more than 70 million military personnel; including 60 million Europeans; were mobilised in one of the largest wars in history. Pictures From History Pictures From History