Political map of East Asia and the Western Pacific 4 September 1905 (Russo-Japanese War): Japan swiftly overran Korea and southern Manchuria, capturing Port Arthur after a prolonged siege (Siege of Port Arthur). In an attempt to gain naval supremacy, Russia sent its European fleet halfway around the world - only to have the Japanese destroy it at Tsushima (Battle of Tsushima). Unsuccessful in the war (Russo-Japanese War) and facing widespread unrest at home (1905 Russian Revolution), the Russians sued for peace (Treaty of Portsmouth).