The July Crisis

In the month that followed, the alliance system mechanically converted a regional incident into a continental war.

• 12. Austria-Hungary, with German backing, issued an ultimatum to Serbia containing demands designed to be rejected
• 13. Serbia accepted most but not all of the demands
• 14. Austria-Hungary declared war on Serbia (July 28, 1914)

15. Russia, the protector of Slavic peoples, mobilized in support of Serbia
16. Germany declared war on Russia, then on France
17. Germany invaded Belgium to attack France, bringing Britain into the war
18. By early August 1914, all major European powers were at war