Tsushima (tsōˈshēmä) [key], two Japanese islands in Korea Strait. The islands are rocky, and fishing is the main occupation. Nearby, in May, 1905, occurred the major naval battle of the Russo-Japanese War. The Russian Baltic fleet, under command of Admiral Rozhdestvenski, suffered nearly total disaster in its encounter with the Japanese fleet under Count Togo. Only a few of the Russian ships escaped to neutral ports or reached their destination (Vladivostok); the majority were sunk or captured. It was in this battle that naval radio was first used (by Count Togo). The defeat convinced Russia that further struggle was hopeless, and in August a treaty of peace was signed at Portsmouth, N.H.