World War 2 involved a global conflict between the Allied forces and the Axis powers. The Allies included Britain, France, the Soviet Union, China, and the United States, while the Axis included Germany, Italy, and Japan. Some key leaders and events included Adolf Hitler rising to power in Germany and enacting fascist rule, Germany invading Poland to start the war in Europe, Japan attacking Pearl Harbor to bring the US into the war, and the US eventually dropping atomic bombs on Hiroshima and Nagasaki, leading to Japan's surrender and the end of World War 2.