World War II took place from September 1, 1939 to September 2, 1945.
World War II ( often abbreviated to WWII or WW2 ) , also known as the Second World War , was a global war that lasted from 1939 to 1945 , although related conflicts began earlier . The Empire of Japan aimed to dominate Asia and the Pacific and was already at war with the Republic of China in 1937 , but the world war is generally said to have begun on 1 September 1939 with the invasion of Poland by Nazi Germany and subsequent declarations of war on Germany by France and the United Kingdom . The war in Europe concluded with an invasion of Germany by the Western Allies and the Soviet Union , culminating in the capture of Berlin by Soviet troops and the subsequent German unconditional surrender on 8 May 1945 . With an invasion of the Japanese archipelago imminent , the possibility of additional atomic bombings , and the Soviet Union 's declaration of war on Japan and invasion of Manchuria , Japan surrendered on 15 August 1945 . Thus ended the war in Asia , cementing the total victory of the Allies .