Question

What started world war II?

Answer 1

The main causes of World War II were nationalistic tensions, unresolved issues, and resentments resulting from the World War I and the interwar period in Europe, plus the effects of the Great Depression in the 1930s.
The culmination of events that led to the outbreak of war are generally understood to be the 1939 invasion of Poland by Germany and Soviet Russia and the 1937 invasion of the Republic of China by the Empire of Japan.
These military aggressions were the result of decisions made by the authoritarian ruling Nazi elite in Germany and by the leadership of the Kwantung Army in Japan. World War II started after these aggressive actions were met with an official declaration of war and/or armed resistance.

Answer 2

World War Two began in September 1939 when Britain and France declared war on Germany following Germany's invasion of Poland.

Although the outbreak of war was triggered by Germany's invasion of Poland, the causes of the war are more complex.

Answer 3

well was it really a "world war" before America got into it? this is a very vague question with so many ways of answering it. if you are at all good at bullpelletting then you will be fine with just 2 or 3 facts.