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 and unblockaded.

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 it.

Russian Vice Admiral Petr Bezobrazov departed Vladivostok on 12 June 1904 with Rossia, Rurik, and Gromoboi under orders to proceed through the eastern Tsushima Channel in the Korean Strait, cruise for two days on known transport routes, and to then double back through the western channel, after which he was to attempt to join his forces to the fleet still blockaded at Port Arthur.

Passing in the opposite direction was the smaller Izumi Maru, which was being used as an unarmed, but unmarked hospital ship transporting sick and wounded men from the front back to Japan.

Gromoboi opened fire with all guns, killing many of the men on deck, including her British captain and senior crewmen, and sinking the ship.