The Sarajevo case, which directly caused World War I, occurred. The case is that the Crown Princes of the Hungarian Empire of Austria are assassinated by Serbs who were one of the “black hands” of anti-Austrian movements. This was the trigger. Austria declared war on Serbia, against which Russia, Serbia’s backing, issued a general mobilization order. On the other hand, as soon as we waited, Germany started the Schleifen Plan, while the British began to attack Germany one after another, declaring war.