World War II, also known as the Second World War, was a global war that lasted from 1939 to 1945. The Second World War was started by Germany in an unprovoked attack on Poland. Britain and France declared war on Germany after Hitler had refused to abort his invasion of Poland.
World War 2 was fought between two groups of countries. On one side were the Axis Powers, including Germany, Italy and Japan. On the other side were the Allies. They included Britain, France, Australia, Canada, New Zealand, India, the Soviet Union, China and the United States of America.