The main cause of world war ii was the rise of the nazi party in germany and its subsequent invasion of other countries the causes can be linked back to world war i the main effects of wwii include the cold war occupation of territories and the widespread destruction in western europe. Effect in history cause effect world war ii world war i causes and effects salem state university world war i causes and effects i causes of world war i ii modern war technology and the human cost iii meanings of world war i causes of world war i 1 growth of german power in central europe challenged great powers france great britain causes of world war i the immediate cause of . The real causes of world war 2 and its devastating effects world war 2 changed the course of history for the world one of the most gruesome wars of all time world war 2 is best known for the bombing of hiroshima and nagasaki by the united states and the holocaust the genocide of six million european jews by nazi germany however there do exist several facts about it which continue to elude most of the people out there. January hitler becomes the chancellor of germany italy invaded abyssinia the league of nations was unable to stop them september 1 1939 germany invades poland causing the start of world war ii japan invades manchuria in china