Answer:
Assassination
Step-by-step explanation:
The assassination of Archduke Franz Ferdinand, heir to the Austro-Hungarian throne, and his wife Sophie in Sarajevo (the capital of the Austro-Hungarian province of Bosnia-Herzegovina) on 28 June 1914 eventually led to the outbreak of the First World War. After more and more countries joined the war their allies and enemies joined it as well dragging the whole world into the conflict all superpowers and small countries.