What incident triggered the beginning of world war 1

Assassination of Arch Franz Ferdinand of Austria

Explanation:

Many events started World War 1, but what specifically triggered it was the Assassination of Arch Franz Ferdinand of Austria. This event was probably the major cause, however, there were other causes such as nationalism (too much pride in one's country) and socialism as well as militarism.

The assassination of Arch Franz Ferdinand, it was done by some Serbian terrorist group

its many islands, high mountains, and remote peninsulas isolated population centers.