Article - The Little Boy and the Fat Boy of World War II The Second World War , commonly known as WW2 , was fought between 1939 and 1945 . Almost all major nations of the world were involved and suffered in this war . Japan’s power was rising in the Asian and Pacific region . Japanese attacks on the USA and British triggered more terrible attacks and counter attacks by the two powers . The world’s powerful nations were divided in two powers - The Allied and the Axis forces . Germany , Japan and Italy formed