The various causes of two world wars were some immediate provocations and some long term causes....
The immediate provocation for world war 1 was the murder of archduke franz ferdinand on 28th june 1914 by a serbian fanatic.
Similarly the immediate provocation for world war 2 is german tanks driving into poland to occupy port of danzing on 1st september 1939.
LONG TERM CAUSES:-
1. Aggressive nationalism
3. Secret alliances
5. Treaty of versailles
6. The failure of league of nations......etc
HOPE IT HELPS.....