The main cause of WWII is the same as that in the first world war, which was mainly allegiances; the Nazi party of Germany invaded Poland, which brought Britain into the war, and then continued to expand across Europe. The primary nations in the allied forces were: Great Britain, France, Poland, USA, Norway, Canada, the USSR, and Denmark, and the primary nations in the Axis Powers were: Germany, Italy, Romania, Bulgaria, and Japan. The main effect of the WWII was the Cold War, a period of about 50 years where the USA and USSR were making threats about nuclear war, as well as the destruction of most of Europe. Another effect was the prevention of Germany to control a Navy. The war ended on September 2nd, 1945, with the surrender of Japan and Germany earlier that year.
