Editing First World War (section)

== Background ==

European politics before 1914 were shaped by competing alliances, expanding armies and disputes over imperial influence. Germany and Austria-Hungary formed the core of the Triple Alliance, although Italy did not enter the war beside them in 1914. France and Russia had a military alliance. The United Kingdom had reached agreements with both states through the Triple Entente.

The [[Balkans]] had become a centre of repeated international crises. Austria-Hungary annexed Bosnia and Herzegovina in 1908. Serbia sought greater influence among South Slavic populations, while Russia supported Serbia as part of its policy in southeastern Europe. The Balkan Wars of 1912 and 1913 weakened Ottoman authority and increased tension between Serbia and Austria-Hungary.

On 28 June 1914, Bosnian Serb nationalist [[Gavrilo Princip]] assassinated [[Archduke Franz Ferdinand of Austria]] and his wife Sophie in [[Sarajevo]]. Austria-Hungary sent Serbia an ultimatum on 23 July. Serbia accepted most demands but rejected provisions that would have allowed Austro-Hungarian officials to operate inside the country. Austria-Hungary declared war on [[Kingdom of Serbia|Serbia]] on 28 July.

Germany declared war on Russia on 1 August and on France on 3 August. German troops entered neutral Belgium on 4 August as part of the planned advance into northern France. The United Kingdom declared war on Germany later that day. Austria-Hungary declared war on Russia on 6 August, completing the expansion of the Balkan crisis into a European war.