The naval Battle off Ulsan (Japanese: 蔚山沖海戦 Urusan'oki kaisen; Russian: Бой в Корейском проливе, Boi v Koreiskom prolive), also known as the Battle of the Japanese Sea or Battle of the Korean Strait, took place on 14 August 1904 between cruiser squadrons of the Imperial Russian Navy and the Imperial Japanese Navy during the Russo-Japanese War, four days after the Battle of the Yellow Sea. Background At the start of the Russo-Japanese War, the bulk of the Russian Pacific Fleet was blockaded within the confines of Port Arthur by the Imperial Japanese Navy. However, the Russian subsidiary naval base at Vladivostok, although shelled by a Japanese squadron under the command of Vice Admiral Dewa Shigetō in March 1904, remained largely undamaged. Located at Vladivostok was a garrison force consisting of the light cruiser and auxiliary cruiser and a stronger Vladivostok Independent Cruiser Squadron consisting of the armored cruisers , , and . This force was under the command of Rear Admiral Karl Jessen from 15 March – 12 June 1904, Vice Admiral Petr Bezobrazov from 12 June – 16 October 1904 and from Jessen again from 15 October 1904 until the end of the war. Commerce raiding operations The Vladivostok Independent Cruiser Squadron made a total of six sorties from Vladivostok for commerce raiding in 1904, sinking a total of 15 transports. The first raid was from 9 to 14 February along the coast of Japan, in which a single transport was sunk. The second was from 24 February to 1 March along the coast of Korea without any results. However, during the third raid from 23 to 27 April, the Russian squadron ambushed Japanese troop transports approaching Gensan in Korea, causing considerable damage. The fourth raid from 12 to 19 June sank several transports in the Tsushima Strait in what was called the "Hitachi Maru Incident", and resulted in the capture of a British transport, Allantown. This was followed by the fifth raid from 28 June – 3 July, again in the Tsushima Strait, in which the British transport Cheltenham was captured. Finally on 17 July to 1 August, the Russian squadron raided the Pacific coast of Japan, sinking one British and one German freighter. As a result of these operations, the Japanese were forced to assign the IJN 2nd Fleet under the command of Vice Admiral Kamimura Hikonojō with considerable resources in an attempt to locate and destroy