The Hitachi Maru Incident (常陸丸事件, Hitachi-maru jiken) was a maritime incident that occurred on June 15, 1904, during the Russo-Japanese War (1904–1905), in which three Japanese military transport ships were attacked and sunk by a Vladivostok-based armored cruiser squadron of the Imperial Russian Navy in the Tsushima Strait.
Background
At the start of the Russo-Japanese War, the bulk of the Russian Pacific Fleet was blockaded at Port Arthur by the Imperial Japanese Navy. However, the Russian naval base at Vladivostok remained operational, housing the Vladivostok Independent Cruiser Squadron under Rear Admiral Karl Jessen, consisting of the armored cruisers Rossiya, Rurik, and Gromoboi. This squadron conducted commerce raiding operations, prompting the Japanese to assign the IJN 2nd Fleet under Vice Admiral Kamimura Hikonojō to locate and destroy it.
The Attack
On 12 June 1904, Russian Vice Admiral Petr Bezobrazov departed Vladivostok with the three cruisers. On 15 June, he sighted two Japanese military transports, Hitachi Maru and Sado Maru, en route to Dalny (Dalian).
- Hitachi Maru was transporting 1,238 people, including 727 men of the 1st Reserve Regiment of the Imperial Guard of Japan and 359 men from the IJA 10th Division, along with critical siege equipment including eighteen Armstrong 11-inch (280 mm) howitzers intended for the attack on Port Arthur.
- Sado Maru was transporting 1,258 people, including 867 members of a railway engineering battalion.
- Izumi Maru, an unarmed but unmarked hospital ship carrying sick and wounded soldiers back to Japan, was also in the area.
The Japanese protected cruiser Tsushima sighted the Russian squadron in heavy fog but could not transmit a warning until 0815 hours due to poor atmospheric conditions and limited wireless range. At 0900, the Russian squadron sighted Izumi Maru; Gromoboi opened fire, killing or wounding over 30 men, and sank the vessel after taking off approximately 100 sick and wounded prisoners. Around 1000, the Russians sighted Sado Maru; Rurik fired two torpedoes into her, killing 239 passengers and crew, though the ship did not sink and later drifted aground on Okinoshima. Gromoboi then approached Hitachi Maru, which showed no sign of surrendering, and opened fire with all guns, killing many on deck—including her British captain—and sinking the ship.
Casualties and Result
The attack resulted in 2 ships sunk, 1 grounded, 1,334 killed, and 112 wounded. The Japanese fleet could not close with the Russian squadron due to deteriorating visibility and reached only 152 survivors from Hitachi Maru.
Aftermath
The incident was a severe blow to Japanese public morale. Memorials were erected at Chidorigafuchi Park in Tokyo, a mass grave for the Imperial Guards was placed in Aoyama Cemetery, and a monument to Sado Maru was built (later moved to Yasukuni Shrine in 1964). Vice Admiral Kamimura received numerous death threats and came under extreme pressure to track down the Russian squadron, which he did at the Battle off Ulsan on 14 August 1904. The Russian squadron continued its raiding operations, seizing the British steamer Allanton off Maizuru on 16 June and sinking two sailing boats the following day.
