The Russo-Japanese War (8 February 1904  5 September 1905)-Russian soldiers patrolling a siberian forest in the cold winter. This war was 'the first great war of the 20th century.' It grew out of rival imperial ambitions of the Russian Empire and the Empire of Japan over Manchuria and Korea. The major theatres of operations were Southern Manchuria specifically the area around the Liaodong Peninsula and Mukden; and the seas around Korea Japan and the Yellow Sea