Claim: World War II had campaigns occurring in Asia and the Pacific Ocean.

The was the historical Japanese nation-state and great power that existed from the Meiji Restoration in 1868 to the enactment of the 1947 constitution of modern Japan .   Imperial Japan 's rapid industrialization and militarization under the slogan led to its emergence as a world power and the establishment of a colonial empire . Economic and political turmoil in the 1920s led to the rise of militarism , eventually culminating in Japan 's membership in the Axis alliance and the conquest of a large part of the Asia-Pacific region .   After several large-scale military successes during the Second Sino-Japanese War -LRB- 1937 -- 1945 -RRB- and the Pacific War , the Empire also gained notoriety for its war crimes against the peoples it conquered . After suffering many defeats and following the Soviet Union 's declaration of war against Japan and invasion of Manchuria , and the atomic bombings of Hiroshima and Nagasaki , however , the Empire surrendered to the Allies on August 15 , 1945 . A period of occupation by the Allies followed the surrender , and a new constitution was created with American involvement in 1947 , officially dissolving the Empire . Occupation and reconstruction continued well into the 1950s , eventually forming the current nation-state whose full title is the `` State of Japan '' or simply rendered `` Japan '' in English .   The Emperors during this time , which spanned the entire Meiji and Taishō , and the lesser part of the Shōwa eras , are now known in Japan by their posthumous names , which coincide with those era names : Emperor Meiji -LRB- Mutsuhito -RRB- , Emperor Taishō -LRB- Yoshihito -RRB- , and Emperor Shōwa -LRB- Hirohito -RRB- .