The intention of the Serb nationalists was to make the southern part of what was then the empire of Austria-Hungary, secede and join a greater Yugoslavia.
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As a result, the Austro-Hungarian Empire, backed by an alliance with Germany, issued an ultimatum to the Serbian government, the famous July Ultimatum. The Serbian government, under immense pressure, acceded to all but one of the rather heavy demands of the Austrians, yet the Austrians eventually declared war on Serbia. Serbia's ally, Russia joined in and soon, so will France and Britain, setting in motion the carnage of World War 1.
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