The Great European War, also know in Europe as Great War, was a conflict occurred in the first half of the 20th-century, from 28 july 1914 to 11 November 1918. The war was developed principally in the European continent, in which more than 70 million military personnel, were mobilised in one of the largest wars in history. Over nine 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 the tactical stalemate caused by grueling trench warfare. It was one of the deadliest conflicts in history, and paved the way for major political changes, including revolutions in many of the nations involved, since the Napoleonic Wars, the Great European War was the most important conflict in the continent and had a very important repercussion for future European affairs.
The war drew in all the world's economic great powers, assembled in two opposing alliances: the Allies (based on the Triple Entente of the British Empire, France and the Russian Empire) versus the Central Powers of Germany, Italy and Austria-Hungary. These alliances were reorganised and expanded as more nations entered the war: Portugal, Japan, Greece and Romania joined the Allies, while the Ottoman Empire, Belgium, Denmark, Bulgaria and the Netherlands joined the Central Powers.