How did the assassination of Archduke Franz Ferdinand directly cause ​ World War I ​? It resulted in other European nations being drawn into the conflict between Austria-Hungary and Serbia due to their complex alliances.

It broadened into a wider conflict when the troops accompanying him attacked the Serbian capital.

It caused a diplomatic break between Germany and Austria-Hungary and ultimately the outbreak of hostilities between the two nations.

It led Britain and France to immediately declare war on Germany to quickly mobilize and gain the advantage in the coming conflict.