Japanese submarine tender Komahashi

Komahashi (駒橋), was an auxiliary vessel operated by the Imperial Japanese Navy, serving during the 1910s and World War II. Her classification changed numerous times during her operational life. Although officially designated as a submarine tender for most of her career, Komahashi very rarely functioned in this role, but was used instead as an oceanographic survey vessel throughout the Pacific.

Background
The Imperial Japanese Navy received its first submarines during the Russo-Japanese War, but these vessels were not operational until after the war ended. During the post-war period, submarine warfare was given a low priority for development, as the early submarines were regarded as unsafe, and useful only for short-range coastal point defense.

Operational career
Komahashi was designed and built as the Cargo ship Komahashi Maru (運送船 駒橋丸) at the Sasebo Naval Arsenal. She was laid down on 7 October 1912 and was launching on 21 May 1913. She was specifically intended for the role of supplying the Imperial Japanese Navy’s Mako Guard District, located in the Pescadores between Taiwan and China. However, with the start of World War I, from 20 January 1914, Komahashi was based at Sasebo Naval District, and was converted into a submarine tender on 23 May 1914. However, soon after, on 16 August 1914, she was re-classified as a 2nd class kaibokan (coastal defense ship) and assigned to the 4th Torpedo Division. On 1 April 1920, her classification was changed to torpedo recovery ship (水雷母艦).

On 1 December 1924, Komahashi was again classified as a submarine tender, however her primary task for the next several years was that of a survey vessel, charting the area around the Pescadores and the China coast.

On 1 October 1931, Komahashi was assigned to the Yokosuka Naval District, and was refitted at the Yokosuka Naval Arsenal in early 1932 with more powerful diesel engines and survey ship facilities, a process that lasted until November 1932. Upon re-launching, she surveyed around the Luzon Strait, the South Pacific Mandate, the Kuril Islands and the Kamchatka Peninsula, collecting data on ocean currents, salinity, subsea topography and fisheries resources. One of her discoveries was the Komahashi Seamount, an underwater volcano at the northern end of the Kyushu-Palau Ridge in the Philippine Sea

On 19 August 1937, Komahashi was assigned to the IJN 3rd Fleet and participated in combat operations along the China coast during the Second Sino-Japanese War. On 10 October 1937, she was assigned to the China Area Fleet.

From June 1939, Komahashi was once again assigned to the Yokosuka Naval District, and assigned to surveying missions and patrols of the South Pacific Mandate area for the potential development of seaplane bases and naval harbors, and was serving in this capacity at the time of the attack on Pearl Harbor on 7 December 1941.

On 7 July 1942, Komahashi participated in the rescue mission for survivors of the SS Haruna Maru, a 10420-ton passenger liner that had run aground off Omaezaki on a transport mission for the Imperial Japanese Army. After the conclusion of the rescue, Komahashi was re-assigned to the IJN 5th Fleet for operations in northern waters.

During August–September 1942 Komahashi surveyed the Aleutian Islands during the Japanese invasion. She was heavily damaged by U.S. aircraft at Kiska on 29 September and was forced to withdraw to Yokosuka Naval Arsenal for repairs. On 1 November, she was once again assigned to the Yokosuka Naval District, where she made 38 runs as a convoy escort and transport in waters around the Japanese home islands throughout 1943.

On 16 January 1944, Komahashi was declared flagship of the 3rd Escort Group, IJN Escort Fleet and based in Owase, Mie Prefecture, escorting shipping around the Kii Peninsula.

On 15 April 1945 Komahashi was assigned to the role of flagship of the 4th Special Attack Division, based at Owase. The division included 60 Shinyo suicide motor boats, 24 Kairyu midget submarines and four Kaiten human torpedoes

It was in this role that she was attacked by Allied aircraft of Task Force 38 on 27 July of that year and sank in shallow waters at Owase. Komahashi was abandoned until the surrender of Japan and officially struck from the navy list on 30 November 1945. On 20 September 1948, she was refloated and towed to Nagoya, where she was salvaged for scrap in 1949.