Answer:
Adolf Hitler began taking over neighboring countries. Britain and France didn't stop him because they didn't want another war to start. BUt they ended up declaring war because Germany invaded Poland after they signed a non aggression pact. Japan took over Manchuria and it risked war with European powers.
Explanation:
France, England and Russia were major empires that had colonies abroad and the reemergence of Germany came to threaten their interests.
The British and French had hoped for a peaceful way to ease so they practised the "Appeasement" policy, where they passively accepted the territorial gains of Germany when it came to annexing Austria, and Czechoslovakia.
They did so as well with Italy, that had occupied and took Ethiopia.
Germany started an aggressive expansionist policy since it wanted to recover and emerge as the dominant nation in the European scenario. They wanted to retailiate from the "Dictate" or Treaty of Versailles that had been perceived as an imposed set of geographical limits that prevented Germany from becoming a power and attaining the status of superpower in Central Europe and beyond.
Germanys "Lebensraum" was the expansionist policy that conflicted with Europeans in their own continent.
The invasion of Poland, in 1945 became the "drop that spills the cup" as Poland was a major Ally to the French. The war with Poland ended quickly in a "Blitzkrieg" and turned soon to the West where France suffered heavily and as well in a short period came to need the imminent support of the British.
Meanwhile in Japan, a series of expansionist movements , in special the Japan invasion of Manchuria, led to Europeans to worry for their outposts in Asia.
