A war that comprised of two alliances (the Axis and the Allies) that went on from 1939 to 1945. The main cause of the war was the German
invasion of Poland, which caused Great Britain and France to declare war on Germany. Germany used a strategy called "Blitzkrieg" or in English terms, "Lightning War" to swiftly take out the French. Before the invasion of Poland, the Germans and Soviets signed the Molotov-Ribbentrop
pact, which was a nonaggression pact which also agreed to split poland between the two nations. This pact would be broken in a few years in what became
Operation Barbarossa, the German invasion of the Soviet Union. After these events, the Japanese bombed Pearl Harbor, which led the United States of America to declare war on Japan. Germany declared war on the US as well. Years later, after many battles and air superiority, the Allies launched a mass invasion of
Normandy of what is called
D-Day. This invasion led to the fall of Germany the year after, when the Soviets took Berlin and when Adolf Hitler killed himself in a bunker underneath Berlin. America then used atomic bombs on Hiroshima and Nagasaki in which the Japanese surrendered after that. Thus, ended the second world war.