the reason for the start of world war 2
World War II The start of the war in Europe is generally held to be 1 September 1939,[9][10] beginning with the German invasion of Poland; the United Kingdom and France declared war on Germany two days later. The dates for the beginning of war in the Pacific include the start of the Second Sino-Japanese War on 7 July 1937,[11][12] or even the Japanese invasion of Manchuria on 19 September 1931.[13][14]