Great Britain was the only country resisting Hitler in the summer of 1940 in Western Europe.
Germany
Nazi Germany.
Belgium
Germany invaded Western Europe in 1939 and 1940.
Most countries were not as prepared for war as Germany was.
The blitzkrieg conquered Western Europe in the Spring of 1940, after taking Poland in September of 1939. He never did take Spain or Switzerland. See the related link(s) listed below for more information:
Nazi Germany it controlled most of France Poland Austria Denmark Czechoslovakia
Great Britain
By the fall of 1940 Germany controlled most of Western Europe. The countries under German rule include but are not limited to France, Belgium, and the Netherlands.
Great Britain
By the end of 1940, Germany had conquered just about every country that had previously opposed it. The one country left unconquered was Great Britain, thanks in large part to the fact that it was protected by the English Channel.