Just like with any war, the causes of World War Two are so vast and varied that it's impossible to pinpoint any one catalyst. In order to get a full picture of what happened, we must consider both the long-term causes and short-term causes, and how they interlinked to prompt the start of the war in September 1939.
Click on the links below to study some of the likely causes of the war, as well as how these causes are related to other possible sources of pressure:
"Causes of WW2". HistoryLearning.com. 2019. Web.