The Battle of Tsushima (Russian: Цусимское сражение, Tsusimskoye srazheniye), commonly known as the “Sea of Japan Naval Battle” (Japanese: 日本海海戦, nihonkai-kaisen) in Japan and the “Battle of Tsushima Strait”, was a major naval battle fought between Russia and Japan during the Russo-Japanese War. It was naval history's only decisive sea battle fought by modern steel battleship fleets, and the first naval battle in which wireless telegraphy (radio) played a critically important role.