What were the principal rivalries and tensions which caused the First World War?

The assassination of the Archduke Franz Ferdinand by a group of terrorists. It pitted the Central Powers and the Triple Entente against each other.

Causes of the First World War is discussed below.

Explanation:

The original causes of World War I incorporated governments, undisclosed agreements, colonialism, and nationalism ego. However, there was one particular event, the shooting of Archduke Ferdinand of Austria, which caused a string of incidents heading to war. The principal short-term reason was the killing of Archduke Franz Ferdinand.