Imperial Japanese Navy

The Imperial Japanese Navy (IJN) (大日本帝國海軍 Dai-Nippon Teikoku Kaigun or 日本海軍 Nippon Kaigun) was the navy of Japan before 1945. It was administered by the Ministry of the Navy of Japan and controlled, somewhat, by the Chief of the Imperial Japanese Navy General Staff at Imperial General Headquarters.

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Ensign of the Imperial Japanese Navy.

The opening of Japan

Japan built her first ocean-going Western-style warships in the beginning of the 17th century, during her first period of contacts with the West. In 1614, the Daimyo of Sendai, in agreement with the Tokugawa Bakufu, built San Juan Bautista, a 500 ton galleon-type ship that transported a Japanese embassy to the Americas, which then continued to Europe. For the following two hundred years however, Japan chose a policy of seclusion, which prohibited the construction of ocean-going ships.

The study of Western shipbuilding resumed in the 1840s, and intensified together with the increased activity of Western shipping along the coasts of Japan, due to the China trade and the development of whaling. In 1852, the government of the Shogun, the Bakufu, fearing further foreign incursions, started the construction of the first post-seclusion Japanese Western-style warship, the Shōhei Maru.

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Kanrin Maru, Japan's first screw-driven steam warship, 1855.

In 1854, Commodore Perry of the United States Navy, obtained the opening of the country to international trade and the establishment of foreign concessions. From that time, the Tokugawa shogun government enforced an active policy of assimilation of Western naval techniques. A naval training school was established in Nagasaki in 1855. Naval students were sent to study in Western naval schools for several years, starting a tradition of foreign-educated future leaders, such as Admiral Enomoto, Admiral Togo, and later on Admiral Yamamoto. French naval engineers were hired to build naval arsenals, such as Yokosuka and Nagasaki.

By the end of the Tokugawa shogunate in 1867, the Japanese navy of the shogun already possessed eight western-style steam warships around the flagship Kaiyō Maru, which were used against pro-imperial forces during the Boshin war, under the command of Admiral Enomoto. Other ships included the Jho Sho Maru, the Ho Sho Maru and the Kagoshima, all built by Thomas Blake Glover in Aberdeen.

Meiji Restoration onward

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Kotetsu (ex CSS Stonewall), Japan's first ironclad, 1869.

From 1868, the restored Meiji Emperor continued with massive reforms to industrialize and militarize Japan in order to prevent it from being overwhelmed by the United States and European powers. During the Meiji period, Japan built up its new navy and broadly based it on the British Royal Navy, they also relied heavily on British and French expertise and bought many ships from British and French shipyards. In 1869, Japan acquired its first ocean-going ironclad warship, the Kotetsu, barely ten years after such ships were first introduced in the West with the launch of the French La Gloire.

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Hosho, the first purpose-designed aircraft carrier in the world (1922)

Very quickly, Japan built up a strong national naval industry. The last major purchase was in 1913 when the battlecruiser Kongo was purchased from the Vickers shipyard.

Although Japan lacked many of the resources of the European powers of the time, by the beginning of the 20th century Japan had, with a lot of help from Britain, France and Germany, created a navy that bested the navies of both China (in 1894-95) and Russia (in 1904-05; see Battle of Tsushima), and by 1920 it was the world's third largest navy.

  • The Japanese Navy was the first in the world to have a wireless communication system, used during the Battle of Tsushima.
  • In 1909 it launched the battleship Satsuma, at the time the largest ship in the world by displacement.
  • In terms of armament, it was the first navy to mount 14-, 16- and 18.1-inch guns.
  • In 1922 it launched the Hosho, the first purpose-designed aircraft carrier in the world.

World War II

(See also the article the Imperial Japanese Navy of World War Two)

In the years before WW II the IJN began to structure itself specifically to fight the US. A long stretch of militaristic expansion and the start of the Second Sino-Japanese war in 1937 had alienated the US and America was seen more often as the enemy of Japan.

In order to combat the numerically superior American navy, the IJN devoted large amounts of resources to creating a force superior in quality to any navy at the time. Out of this effort came numerous achievements:

, the largest  in history, in 1941.
Yamato, the largest battleship in history, in 1941.


  • Shells designed for penetration below the target ship's waterline.
  • The fabled Long Lance torpedo.
  • Superb night-fighting techniques.
  • Aircraft carriers, such as the Shokaku and Zuikaku, exceeding any in the world in performance and capability, until the wartime development of the American Essex-class aircraft carrier.
  • The I-400-class submarines, the largest submarines of World War II, and the only ones besides the French submarine Surcouf to carry aircraft.
  • A competent naval air force designed around the best naval fighter plane of the beginning of the war, the Mitsubishi Zero.
  • Yamato, the largest and most heavily-armed battleship in history, launched in 1941.


Consequently, at the beginning of World War II, Japan probably had the most sophisticated Navy in the world. And it was organized as follows:

  • Navy Air Service - includes both the 1st Carrier Fleet and the 11th Air Fleet.
  • Combined Fleet (Rengo Kantai):
    • Fleet Headquarters - Was at Tokyo then moved to Hiroshima and finally to Keio University in the Tokyo suburb of Hiyodashi.
    • 1st Battleship Fleet - Based at Hiroshima with (10 Battleships, 3 seaplane carriers, 10 cruisers and 30 destroyers
    • 2d Scouting Fleet - Based at Hainan with 13 heavy cruisers and 32 destroyers
    • 3d Blockade and Transport Fleet - Based in Formosa with 5 cruisers, 12 destroyers, 6 minelayers, and 1 escort
    • 4th Pacific Mandate Islands (South Pacific Mandate) Fleet - Based at Truk Lagoon with 4 cruisers, 1 seaplane carrier, 12 destroyers, 2 minelayers
    • 5th Northern Waters Fleet - Based at Maizuru/Ominato with 2 cruisers
    • 6th Submarine Fleet - Based at Kwajalein with 3 cruisers and 63 submarines
    • 8th Fleet - added later in war
    • 1st Carrier Fleet - 10 aircraft carriers; 6 fleet, 3 light and one training with an Air Corps (Kokutai and later called Koku Sentai) of 1500 pilots and over 1500 aircraft
    • 11th Air Fleet - Shore based naval aircraft
    • Southern Fleet - Indochina
  • China Theater Fleet
    • Fleet Headquarters - Shanghai
    • 1st China Fleet
    • 2d China Fleet
    • 3d China Fleet
    • Manchukuo Flotilla - river and coastal patrol
    • Kwantung Naval detachment guard
  • Southwest Area Fleet - added in 1942
  • Four Naval districts
  • Five Guard Districts
  • 8 Base Forces at:

-Chisima Islands (joint at Japanese Army detachments)

-Karafuto (some little detachments in ports)

These directly controlled 90 armed merchant ships (called maru), submarine chasers, gunboats, 6 minelayers, 42 minesweepers and 46 auxiliaries. They also controlled the IJN Land Forces.


Although the Japanese Navy enjoyed spectacular success during the first part of the hostilities, American forces ultimately managed to gain the upper hand through technological upgrades to its air and naval forces, and a vastly stronger industrial output. Japan's reluctance to use their submarine fleet for commerce raiding and failure to secure their communications also added to their defeat.

During the last phase of the war the Imperial Japanese Navy resorted to a series of desperate measures, including Kamikaze (suicide) actions.

Self-Defense Forces

Following Japan's surrender to the United States at the conclusion of World War II, and Japan's subsequent occupation, Japan's entire imperial military was dissolved in the new 1947 constitution which states, "The Japanese people forever renounce war as a sovereign right of the nation and the threat or use of force as a means of settling international disputes."

Japan's current navy falls under the umbrella of the Japan Self-Defense Forces (JSDF).


  • KAIGUN, Strategy, tactics and technology of the Imperial Japanese Navy, 1887-1941,David C. Evans & Mark R. Peattie, Naval Institute Press, Annapolis, Maryland [ISBN 0870211927]
  • The origins of Japanese Trade Supremacy, Development and technology in Asia from 1540 to the Pacific War, Christopher Howe, The University of Chicago Press [ISBN 0226354857]
  • A Battle History of The Imperial Japanese Navy, Paul S. Dull

Major actions

See also

External links

de:Imperiale Japanische Marine ja:大日本帝国海軍


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