On the 23^rd July 1914, Austria-Hungary issued an ultimatum to Serbia specifically designed to be rejected and lead to war between the two countries.

The ultimatum was delivered at 6pm by the Austro-Hungarian ambassador to Belgrade, with a deadline of 48 hours within which the Serbian government had to respond. They accepted all but one of the numerous demands, which led Austria-Hungary to declare war three days later on 28^th July.

Austria-Hungary had been concerned about the growing power of Serbia, and was keen to find a way to weaken the government and stop it taking over the Southern Slavic populations of the northern Balkans, and especially Bosnia, under the banner of pan-Slavism. To the government officials who favoured war, the assassination of Archduke Franz Ferdinand, the heir to the Austro-Hungarian throne, on the 28^th June was the perfect excuse.

Following the assassination, Germany had given Austria-Hungary assurances that it would support military action against Serbia, in what is known as the ‘Blank Cheque’ of 5^th July. Acting with the knowledge that the strongest army in Europe was on their side, the Austro-Hungarian Crown Council began to discuss how best to justify a war against Serbia. They decided that an ultimatum containing unacceptable demands would be the best course of action, and finally agreed the wording on the 19^th.

After Serbia’s refusal of the sixth point in the ultimatum, Austria-Hungary declared war. Although it was intended to remain localised, the network of European alliances that had developed from the late 19^th Century soon saw the conflict develop into the First World War.