was an admiral in the

Imperial Japanese Navy The Imperial Japanese Navy (IJN; Kyūjitai: Shinjitai: ' 'Navy of the Greater Japanese Empire', or ''Nippon Kaigun'', 'Japanese Navy') was the navy of the Empire of Japan from 1868 to 1945, Potsdam Declaration, when it was dissolved followin ...

and Naval Minister during

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

Biography

Oikawa was born into a wealthy family in rural Koshi County,

Niigata Prefecture is a Prefectures of Japan, prefecture in the Chūbu region of Honshu of Japan. Niigata Prefecture has a population of 2,131,009 (1 July 2023) and is the List of Japanese prefectures by area, fifth-largest prefecture of Japan by geographic area ...

, but was raised in Morioka city,

Iwate prefecture is a Prefectures of Japan, prefecture of Japan located in the Tōhoku region of Honshu. It is the second-largest Japanese prefecture (behind Hokkaido) at , with a population of 1,165,886 (as of July 1, 2023). Iwate Prefecture borders Aomori Pre ...

in northern Japan. He was a graduate of the 31st class of the Imperial Japanese Naval Academy, ranking 76th out of 188 cadets. As a

midshipman A midshipman is an officer of the lowest Military rank#Subordinate/student officer, rank in the Royal Navy, United States Navy, and many Commonwealth of Nations, Commonwealth navies. Commonwealth countries which use the rank include Royal Cana ...

, he served on the cruisers and . During the

Russo-Japanese War The Russo-Japanese War (8 February 1904 – 5 September 1905) was fought between the Russian Empire and the Empire of Japan over rival imperial ambitions in Manchuria and the Korean Empire. The major land battles of the war were fought on the ...

, still as a

, he served on the during the

Battle of Tsushima The Battle of Tsushima (, ''Tsusimskoye srazheniye''), also known in Japan as the , was the final naval battle of the Russo-Japanese War, fought on 27–28 May 1905 in the Tsushima Strait. A devastating defeat for the Imperial Russian Navy, the ...

. As a

lieutenant A lieutenant ( , ; abbreviated Lt., Lt, LT, Lieut and similar) is a Junior officer, junior commissioned officer rank in the armed forces of many nations, as well as fire services, emergency medical services, Security agency, security services ...

, Oikawa served on the cruiser , and the battleship . He was given his first command, the

destroyer In naval terminology, a destroyer is a fast, maneuverable, long-endurance warship intended to escort larger vessels in a fleet, convoy, or carrier battle group and defend them against a wide range of general threats. They were conceived i ...

on 28 April 1911. He subsequently served on the , before attending the Naval Staff College in 1914. On graduation, Oikawa was promoted to lieutenant commander, and was appointed aide-de-camp to

Crown Prince A crown prince or hereditary prince is the heir apparent to the throne in a royal or imperial monarchy. The female form of the title, crown princess, is held by a woman who is heir apparent or is married to the heir apparent. ''Crown prince ...

Hirohito , Posthumous name, posthumously honored as , was the 124th emperor of Japan according to the traditional order of succession, from 25 December 1926 until Death and state funeral of Hirohito, his death in 1989. He remains Japan's longest-reigni ...

in 1915–1922. After his promotion to captain on 1 December 1923, Oikawa was assigned the cruiser , followed by the the following year. He then served in a number of staff positions until his promotion to

rear admiral Rear admiral is a flag officer rank used by English-speaking navies. In most European navies, the equivalent rank is called counter admiral. Rear admiral is usually immediately senior to commodore and immediately below vice admiral. It is ...

on 10 December 1928. In 1930, Oikawa was appointed to the

Imperial Japanese Navy General Staff The was the highest organ within the Imperial Japanese Navy (IJN). In charge of planning and operations, it was headed by an Admiral headquartered in Tokyo. History Created in 1893, the Navy General Staff took over operational (as opposed to a ...

, and in 1932 became Director of the Imperial Japanese Naval Academy. He was promoted to

vice admiral Vice admiral is a senior naval flag officer rank, usually equivalent to lieutenant general and air marshal. A vice admiral is typically senior to a rear admiral and junior to an admiral. Australia In the Royal Australian Navy, the rank of Vice ...

on 15 November 1933. Oikawa strongly supported the

London Naval Treaty The London Naval Treaty, officially the Treaty for the Limitation and Reduction of Naval Armament, was an agreement between the United Kingdom, Empire of Japan, Japan, French Third Republic, France, Kingdom of Italy, Italy, and the United Stat ...

while a member of the Imperial Japanese Navy General Staff, and was thus a member of the Treaty Faction within the navy. Oikawa was subsequently appointed Commander in Chief of the IJN 3rd Fleet (1935), Imperial Japanese Navy Aviation Bureau (1936), China Area Fleet (1938) and

Yokosuka Naval District was the first of four main administrative districts of the pre-war Imperial Japanese Navy. Its territory included Tokyo Bay and the Pacific Ocean, Pacific coasts of central and northern Honshū from the Kii Peninsula to Shimokita Peninsula. Its h ...

(1940). He was promoted to full

admiral Admiral is one of the highest ranks in many navies. In the Commonwealth nations and the United States, a "full" admiral is equivalent to a "full" general in the army or the air force. Admiral is ranked above vice admiral and below admiral of ...

on 15 November 1939. Oikawa was appointed as Minister of the Navy in the second and third cabinets of

Prime Minister A prime minister or chief of cabinet is the head of the cabinet and the leader of the ministers in the executive branch of government, often in a parliamentary or semi-presidential system. A prime minister is not the head of state, but r ...

Fumimaro Konoe was a Japanese politician who served as Prime Minister of Japan from 1937 to 1939 and from 1940 to 1941. He presided over the Japanese invasion of China in 1937 and breakdown in relations with the United States, which shortly after his t ...

between 5 September 1940 and 18 October 1941. While Navy Minister, he strove to maintain ties with the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

, and instructed his naval attachés in

Washington DC Washington, D.C., formally the District of Columbia and commonly known as Washington or D.C., is the capital city and Federal district of the United States, federal district of the United States. The city is on the Potomac River, across from ...

to work together with the Japanese ambassador to prevent war from breaking out. Likewise, he strongly opposed suggestions that Japan should declare war on the

Soviet Union The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

in early 1941.Fuller, Shokan: Hirohito's Samurai He continued to serve as Naval Councilor to near the end of World War II and was Chief of the Navy General Staff in late 1944 but resigned in May 1945 and was replaced by an Ōita native Toyoda Soemu in an attempt to soften down the

Imperial Japanese Army The Imperial Japanese Army (IJA; , ''Dai-Nippon Teikoku Rikugun'', "Army of the Greater Japanese Empire") was the principal ground force of the Empire of Japan from 1871 to 1945. It played a central role in Japan’s rapid modernization during th ...

's Ōita-born leadership. Oikawa retired from active duty on 5 September 1945.

References

Books

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Notes

External links

* * {{DEFAULTSORT:Oikawa, Koshiro 1883 births 1958 deaths People from Morioka, Iwate Imperial Japanese Navy admirals Japanese military personnel of the Russo-Japanese War Japanese admirals of World War II Ministers of the Imperial Japanese Navy