On 28 July 1914, Austria-Hungary declared war on Serbia because of the Assassination of Archduke Franz Ferdinand. Within days, long-standing mobilization plans went into effect to initiate invasions or guard against them and Russia, France and Britain stood arrayed against Austria and Germany in what at the time was called the "Great War", and was later named "World War I" or the "First World War". Austria thought in terms of one small limited war involving just the two countries. It did not plan a wider war such as exploded in a matter of days.

Leopold Anton Johann Sigismund Josef Korsinus Ferdinand Graf Berchtold von und zu Ungarschitz, Frättling und Püllütz was an Austro-Hungarian politician, diplomat and statesman who served as Imperial Foreign Minister at the outbreak of World War I.