Ultimatums and Declarations

Hötzendorf and Berchtold could now act. Berchtold drew up an ultimatum with terms that he knew would be unacceptable to Serbia. He also set a 48-hour time limit for Serbia's response. In a carefully worded reply, Serbia agreed to all of the conditions of the ultimatum, except for the Austrian demand to conduct an investigation and trial in Serbia. The Serbians proposed that if this reply was unsatisfactory, the question of Serbia's guilt in the assassination should be submitted to the Hague Tribunal for arbitration. Austria-Hungary, declaring that Serbia's reply was unacceptable, severed diplomatic relations with Serbia and ordered mobilization.

Russia pledged full support for Serbia and ordered mobilization on July 25. The next day, Sir Edward Grey, the British foreign minister, proposed a conference of the Great Powers to resolve the crisis, but Austria-Hungary was unwilling to attend. On July 27 France ordered mobilization in support of Russia. On July 31 Germany gave Russia an ultimatum that threatened mobilization if Russia did not rescind its mobilization orders within 12 hours.

Austria-Hungary declared war on Serbia on July 28 and then began shelling Belgrade (the capital of Serbia). Russia did not respond to Germany's ultimatum. Germany declared war on Russia on August 1, and on France on August 3. France and Britain declared war on Germany on August 3 and 4, respectively. Austria-Hungary declared war on Russia on August 6.