World War I, also known as the First World War, the Great War, and The War to End All Wars, is a global war which takes place primarily in Europe from 1914 to 1918.

Over 40 million casualties result, including approximately 20 million military and civilian deaths.

Over 60 million European soldiers are mobilized from 1914 to 1918.The context which helps explain the war is increasing economic and military competition between Britain and Germany.

Germany's industrial economy is fast overtaking Britain's, but the German economy lacks a major empire to back up its home economy.

The economic race between the two powers has led to military competition, in particular the building of numerous "Dreadnoughts" -powerful military ships.The immediate cause of the war is the June 28, 1914 assassination of Archduke Franz Ferdinand, heir to the Austro-Hungarian throne, by Gavrilo Princip, a Bosnian Serb citizen of Austria-Hungary and member of the Black Hand.

The retaliation by Austria-Hungary against the Kingdom of Serbia activates a series of alliances that sets off a chain reaction of war declarations.

Within a month, much of Europe is in a state of open warfare.The war is propagated by two major alliances.

The Entente Powers initially consist of France, the United Kingdom, Russia, and their associated empires and dependencies.

Numerous other states join these allies, most notably Italy in April 1915, and the United States in April 1917.

The Central Powers, so named because of their central location on the European continent, initially consist of Germany and Austria-Hungary and their associated empires.

The Ottoman Empire joins the Central Powers in October 1914, followed a year later by Bulgaria.

By the conclusion of the war, only The Netherlands, Switzerland, Spain and the Scandinavian nations remain officially neutral among the European countries, though many of those provide financial and material support to one side or the other.The fighting of the war mostly takes place along several fronts that broadly encircle the European continent.

The Western Front is marked by a system of trenches, breastworks, and fortifications separated by an area known as no man's land.

These fortifications stretch 475 miles (more than 600 kilometres) and precipitate a style of fighting known as trench warfare.

On the Eastern Front, the vast eastern plains and limited rail network prevents a trench warfare stalemate, though the scale of the conflict is just as large as on the Western Front.

The Middle Eastern Front and the Italian Front also see heavy fighting, while hostilities also occur at sea, and for the first time, in the air.The war is ended by several treaties, most notably the Treaty of Versailles, signed on 28 June 1919, though the Allied powers had had an armistice with Germany in place since 11 November 1918.

One of the most striking results of the war is a large redrawing of the map of Europe.

All of the Central Powers lose territory, and many new nations are created.

The German Empire loses its colonial possessions and is saddled with accepting blame for the war, as well as paying punitive reparations for it.

The Austro-Hungarian and Ottoman empires are completely dissolved.

Austria-Hungary is carved up into several successor states including Austria, Hungary, Czechoslovakia, and Yugoslavia.

The Ottoman Empire disintegrates, and much of its non-Anatolian territory is awarded as protectorates of various Allied powers, while the remaining Turkish core is reorganized as the Republic of Turkey.

The Russian Empire, which had withdrawn from the war in 1917, loses much of its western frontier as the newly independent nations of Estonia, Finland, Latvia, Lithuania, and Poland are carved from it.

After the war, the League of Nations is created as an international organization designed to avoid future wars by giving nations a means of solving their differences diplomatically.

The First World War marks the end of the world order which had existed after the Napoleonic Wars, and is an important factor in the outbreak of the Second World War.