The Russo-Japanese War (8 February 1904 - 5 September 1905) was the first great war of the 20th century which grew out of the rival imperial ambitions of the Russian Empire and Japanese Empire over Manchuria and Korea. The major theatres of operations were Southern Manchuria, specifically the area around the Liaodong Peninsula and Mukden, the seas around Korea, Japan, and the Yellow Sea. The resulting campaigns, in which the Japanese military attained victory over the Russian forces arrayed against them, were unexpected by world observers. As time transpired, these victories would transform the balance of power in East Asia, resulting in a reassessment of Japan's recent entry onto the world stage. The embarrassing string of defeats inflamed the Russian people's dissatisfaction with their inefficient and corrupt Tsarist government, and proved a major cause of the Russian Revolution of 1905.