World War I, Events
Standing
Concerns Description
Currently States World War I was a global conflict fought from 1914 to 1918, chiefly among the great powers of Europe and eventually drawing in the United States, the Ottoman Empire and much of the colonized world, that killed an estimated fifteen to twenty two million people and destroyed the pre-war European order of dynastic empires. Its trigger was the assassination of Archduke Franz Ferdinand, heir to the Austro-Hungarian throne, by the Bosnian Serb Gavrilo Princip in Sarajevo on 28 June 1914, but the crisis that followed, conventionally called the July Crisis, turned a localized Balkan dispute into a general war through a chain of alliance commitments and mobilization decisions. Germany gave Austria-Hungary an unconditional guarantee of support, the so called blank cheque, on 5 July; Austria-Hungary issued Serbia a deliberately unacceptable ultimatum on 23 July and declared war on 28 July; Russia's general mobilization in Serbia's defense on 30 July drew a German ultimatum demanding it stand down, and when that expired unanswered, Germany declared war on Russia on 1 August and on France on 3 August. Germany's invasion of Belgium on 4 August, in violation of an 1839 treaty Britain had guaranteed, brought Britain and its empire into the war the same day, making it a global conflict within a single week. On the Western Front the war settled by late 1914 into trench warfare across a line running from the Belgian coast to Switzerland, where industrialized firepower, machine guns, heavy artillery and eventually poison gas and tanks produced enormous casualties for minimal territorial change, at battles such as Verdun and the Somme in 1916. The Eastern Front, the Gallipoli campaign against the Ottoman Empire, war in the Middle East and Africa, and an unrestricted submarine campaign that helped bring the United States into the war in April 1917 made this the first war fought on a genuinely worldwide scale. Russia's own 1917 revolutions took it out of the war, while the United States' entry and Germany's failed spring 1918 offensive turned the balance decisively against the Central Powers, who sued for peace; an armistice took effect on 11 November 1918, followed by the Treaty of Versailles in 1919. Historians remain divided over how to apportion responsibility for the war's outbreak among the great powers, and over whether the July Crisis reflects deliberate aggression, systemic failure, or both.
Source Outbreak of the First World War (Imperial War Museums)