Russo-Japanese War

Russo-Japanese War (1904–05), culmination of rivalry in the Far East between powers who sought expansion at the expense of the decaying Chinese empire. Russia occupied Manchuria during the Boxer Rebellion and coveted Korea, dominated the region and refused to share with Japan its position of influence. As a result, the Japanese attacked the Russian naval base of Port Arthur (now Lüshun, China), defeated the Russians at Mukden (now Shenyang) in Manchuria, and destroyed the Russian Baltic fleet in the Battle of Tsushima. Mediation by U.S. president Theodore Roosevelt ended the war in the Treaty of Portsmouth (1905). Russia ceded territory to Japan, recognized Japan's dominance in Korea, and returned Manchuria to China. Russia's disastrous defeat was one immediate cause of the 1905 Russian Revolution.