The identification of the causes of World War I remains a debated issue. World War I began in the Balkans on July 28, 1914, and hostilities ended on November 11, 1918, leaving 17 million dead and 25 million wounded. Moreover, the Russian Civil War can in many ways be considered a continuation of World War I, as can various other conflicts in the direct aftermath of 1918.
Scholars looking at the long term seek to explain why two rival sets of powers (the German Empire and Austria-Hungary against the Russian Empire, France, the British Empire and later the United States) came into conflict by 1915. They look at such factors as political, territorial and economic competition; militarism, a complex web of alliances and alignments; imperialism, the growth of nationalism; and the power vacuum created by the decline of the Ottoman Empire. Other important long-term or structural factors that are often studied include unresolved territorial disputes, the perceived breakdown of the European balance of power, convoluted and fragmented governance, arms races and security dilemmas, a cult of the offensive, and military planning.
Scholars seeking short-term analysis focus on the summer of 1914 and ask whether the conflict could have been stopped, or instead whether deeper causes made it inevitable. Among the immediate causes were the decisions made by statesmen and generals during the July Crisis, which was triggered by the assassination of Archduke Franz Ferdinand of Austria by the Bosnian Serb nationalist Gavrilo Princip, who had been supported by a nationalist organization in Serbia. The crisis escalated as the conflict between Austria-Hungary and Serbia was joined by their allies Russia, Germany, France, and ultimately Belgium and the United Kingdom. Other factors that came into play during the diplomatic crisis leading up to the war included misperceptions of intent (such as the German belief that Britain would remain neutral), the fatalistic belief that war was inevitable, and the speed with which the crisis escalated, partly due to delays and misunderstandings in diplomatic communications.