Austria-Hungary Declares War on Russia

Opening hostilities Confusion among the Central Powers The strategy of the Central Powers suffered from miscommunication.

Germany had promised to support Austria–Hungary’s invasion of Serbia, but interpretations of what this meant differed. Austro-Hungarian leaders believed Germany would cover its northern flank against Russia. Germany, however, envisioned Austria–Hungary directing the majority of its troops against Russia, while Germany dealt with France. This confusion forced the Austro-Hungarian Army to divide its forces between the Russian and Serbian fronts.

On September 9, 1914 the Septemberprogramm, a plan which detailed Germany's specific war aims and the conditions that Germany sought to force upon the Allied Powers, was outlined by German Chancellor Theobald von Bethmann Hollweg.

On 28 June 1914, Gavrilo Princip, a Bosnian-Serb student and member of Young Bosnia, assassinated the heir to the Austro-Hungarian throne, Archduke Franz Ferdinand of Austria in Sarajevo, Bosnia. This began a period of diplomatic manoeuvering between Austria-Hungary, Germany, Russia, France and Britain called the July Crisis. Wanting to end Serbian interference in Bosnia conclusively, Austria–Hungary delivered the July Ultimatum to Serbia, a series of ten demands which were deliberately unacceptable, made with the intention of deliberately initiating a war with Serbia. When Serbia acceded to only eight of the ten demands levied against it in the ultimatum, Austria–Hungary declared war on Serbia on 28 July 1914. Strachan argues "Whether an equivocal and early response by Serbia would have made any difference to Austria-Hungary's behaviour must be doubtful. Franz Ferdinand was not the sort of personality who commanded popularity, and his demise did not cast the empire into deepest mourning".