For Chamberlain and French Prime Minister Daladier, Germany invading Poland was the last straw. They declared war on the 3rd September 1939, starting the Second World War. For nine months, nothing happened. Then Germany started invading again. Norway, Denmark, the Netherlands and Belgium all crumbled under the Blitzkrieg power, and finally even France was invaded. All of Europe, excepting neutral countries, Italy and Eastern Europe (invaded by Russia, who had a truce with Germany) was invaded.