Which factor played the most significant role in the start of World War 2

there are multiple factors that played an important role in the start of World War II. one of the most important ones is the Treaty of Versailles, that ended World War I. the Treaty had clauses that forced Germany to demilitarize its armed forces, it took territories that was once under German control, and it made the country paid for expensive war reparations to other countries, that put its economy in a depression.. these measures created, in the long term, a sense of revenge in German's society. these feeling of revenge is associated with the rise of Hitler to power because of his message to take Germany back to the place of power it once had.

Explanation:

c]extended voting rights to african americans

united states reinforcements contributed greatly to three allied victories in france at: cantigny (first major american battle), argonne (the largest in the united states military history, involving 1.2 million american soldiers), and château-thierry (one of the first actions under general pershing).