What countries in Europe were involved in World War II?
All were affected by it. Even the small countries. Russia, Italy, France, Britain were the main agressors in Europe, but the USA joined in later on which turned the tide of the war. The Germans had allies in Italy, Japan, and the austrohungarian empire I think (that may have been WW1) and they had Romania. Britain would have had the likes of India, South Africa, their colonies etc such as australia new zealand and canada. When I went to Belgium I met two old women who said when the germans had invaded, they recalled running from them in a huge group of people.
