Imperial Japanese Navy

Origins

Japan has a long history of naval interaction with the Asian continent, involving transportation of troops between Korea and Japan, starting at least with the beginning of the Kofun period in the 3rd century.

Following the attempts at Mongol invasions of Japan by Kubilai Khan in 1274 and 1281, Japanese wakō became very active in plundering the coast of China.

Japan undertook major naval building efforts in the 16th century, during the Warring States period, when feudal rulers vying for supremacy built vast coastal navies of several hundred ships. Around that time Japan may have developed one of the first ironclad warships when Oda Nobunaga, a daimyō, had six iron-covered Oatakebune made in 1576. In 1588 Toyotomi Hideyoshi issued a ban on Wakō piracy; the pirates then became vassals of Hideyoshi, and comprised the naval force used in the Japanese invasion of Korea (1592–1598).

Japan built her first large ocean-going warships in the beginning of the 17th century, following contacts with the Western nations during the Nanban trade period. In 1613, the daimyō of Sendai, in agreement with the Tokugawa Bakufu, built Date Maru, a 500 ton galleon-type ship that transported the Japanese embassy of Hasekura Tsunenaga to the Americas, which then continued to Europe. From 1604 the Bakufu also commissioned about 350 Red seal ships, usually armed and incorporating some Western technologies, mainly for Southeast Asian trade.

Western studies and the end of Seclusion

For more than 200 years, beginning in the 1640s, the Japanese policy of seclusion ("sakoku") forbade contacts with the outside world and prohibited the construction of ocean-going ships on pain of death. Contacts were maintained, however, with the Dutch through the port of Nagasaki, the Chinese also through Nagasaki and the Ryukyus and Korea through intermediaries with Tsushima. The study of Western sciences, called "rangaku" through the Dutch enclave of Dejima in Nagasaki led to the transfer of knowledge related to the Western technological and scientific revolution which allowed Japan to remain aware of naval sciences, such as cartography, optics and mechanical sciences, seclusion however, led to loss of any naval and maritime traditions the nation possessed.

Apart from Dutch trade ships no other Western vessels were allowed to enter Japanese ports, a notable exception was during the Napoleonic wars, when neutral ships flew the Dutch flag. However frictions with foreign ships started from the beginning of the 19th century. The Nagasaki Harbour Incident involving the HMS Phaeton in 1808 and other subsequent incidents in the following decades led to the Shogunate to enact an Edict to Repel Foreign Vessels. Western ships which were increasing their presence around Japan due to whaling and the trade with China began to challenge the seclusion policy.

The Morrison Incident in 1837 and news of China's defeat during the Opium War, however, led to the Shogunate to repeal the law to execute foreigners and instead to adopt the Order for the Provision of Firewood and Water. The shogunate also began to strengthen the nation's coastal defenses. Many Japanese realized that traditional ways would not be sufficient to repel further intrusions and western knowledge was utilized through the Dutch at Dejima to reinforce Japan's capability to repel the foreigners; field guns, mortars and firearms were obtained and coastal defenses reinforced. Numerous attempts to open Japan ended in failure in part to Japanese resistance, this was until the early 1850s.

During 1853 and 1854, American warships under the command of Commodore Matthew Perry entered Edo Bay and made demonstrations of force requesting trade negotiations. After two hundred years of seclusion the 1854 Convention of Kanagawa led to the opening of Japan to international trade and interaction. This was soon followed by the 1858 Treaty of Amity and Commerce and treaties with other powers.

Development of Shogunal and Domain naval forces

As soon as Japan opened up to foreign influences, the Tokugawa shogunate recognized the vulnerability of the country from the sea and initiated an active policy of assimilation and adoption of Western naval technologies. In 1855, with Dutch assistance, the Shogunate acquired its first steam warship, Kankō Maru, and began using it for training, establishing a Naval Training Center at Nagasaki.

Samurai such as the future Admiral Enomoto Takeaki (1836–1908) were sent by the Shogunate to study in the Netherlands for several years. In 1859 the Naval Training Center relocated to Tsukiji in Tokyo. In 1857 the Shogunate acquired its first screw-driven steam warship Kanrin Maru and used it as an escort for the 1860 Japanese delegation to the United States. In 1865 the French naval engineer Léonce Verny was hired to build Japan's first modern naval arsenals, at Yokosuka and Nagasaki. In 1867–1868 a British Naval mission headed by Commander Richard Tracey went to Japan to assist the development of the Japanese Navy and to organize the naval school of Tsukiji.

The Shogunate also allowed and then ordered various domains to purchase warships and to develop naval fleets, Satsuma, especially, had petitioned the Shogunate to build modern naval vessels. A naval center had been set up by the Satsuma domain in Kagoshima, students were sent abroad for training and a number of ships were acquired. The domains of Choshu, Hizen, Tosa and Kaga joined Satsuma in acquiring ships. This was not enough to prevent the British from bombarding Kagoshima in 1863 or the Allied bombardments of Shimonoseki in 1863–64.

By the mid 1860s the Shogunate had a fleet of eight warships and thirty-six auxiliaries. Satsuma (which had the largest domain fleet) had nine steamships, Choshu had five ships plus numerous auxiliary craft, Kaga had ten ships and Chikuzen eight. Numerous smaller domains also had acquired a number of ships. However these fleets resembled maritime organizations rather than actual navies with ships functioning as transports as well as combat vessels, they were also manned by personnel who lacked experienced seamanship except for coastal sailing and who had virtually no combat training.

Creation of the Imperial Japanese Navy (1868–72)

The Meiji Restoration in 1868 led to the overthrow of the Shogunate. From 1868, the newly formed Meiji government continued with reforms to centralize and modernize Japan.

Boshin war

Although the Tokugawa shogunate had been overthrown, tensions between the former ruler and the restoration leaders led to the Boshin War. The early part of the conflict largely involved land battles with naval forces playing a minimal role transporting troops from western to eastern Japan. Only the Battle of Awa was significant, this was also one of the few Tokugawa successes of the war. Tokugawa Yoshinobu eventually surrendered after the fall of Edo and as a result most of Japan accepted the emperor's rule, however resistance continued in the North.

On 26 March 1868, the first naval review in Japan was held in Osaka Bay, with six ships from the private domain navies of Saga, Chōshū, Satsuma, Kurume, Kumamoto and Hiroshima participating. The total tonnage of these ships was 2,252 tons, which was far smaller than the tonnage of the single foreign vessel (from the French Navy) that also participated. The following year, in July 1869, the Imperial Japanese Navy was formally established, two months after the last combat of the Boshin War.

Enomoto Takeaki, admiral of the Shogun's navy, also refused to surrender all his ships, remitting just four ships, and escaped to northern Honshū with the remnants of the Shogun's Navy, which were eight steam warships and 2,000 men. Following defeat of resistance on Honshū, Enomoto Takeaki later fled to Hokkaidō where he established the breakaway Republic of Ezo. A military force was dispatched by the new government to defeat the rebels culminated with the Naval Battle of Hakodate in 1869. The French-built ironclad Kotetsu, originally ordered by the Tokugawa shogunate, was received by the Imperial side and was used decisively towards the end of the conflict.

Consolidation

In February 1868 the government had placed all captured Shogunate naval vessels under the Navy Army affairs section. In the following months, military forces of the government were put under several organizations which were created and then disbanded until the creation of the establishment of Ministry of Military Affairs (Hyōbushō). For the first two years of the Meiji state no national, centrally controlled navy existed, the Meiji government only administered those Tokugawa vessels captured from the early phase of the Boshin war. All other naval vessels remained under the control of the various domains which had been acquired during the Bakumatsu period. The naval forces mirrored that of the political environment of Japan at the time in which the domains retained their political as well as military independence from the imperial government. Katsu Kaishū a former Tokugawa navy leader was brought into the government because of his naval experience and his ability to control Tokugawa personnel who retained positions in the government naval forces. Upon assuming office Katsu Kaishu recommended the rapid centralization of all naval forces government and domain under one agency. However, the nascent Meiji government at the time did not have the necessary political and military force to implement it and so like much of the government the naval forces retained a decentralized structure in most of 1869 through 1870.

The incident involving Enomoto Takeakis' refusal to surrender and his escape to Hokkaidō with a large part of former Tokugawa Navy's best warships embarrassed the Meiji government politically. The imperial side had to rely on considerable naval assistance from the most powerful domains as the government did not have enough naval power to put down the rebellion on its own. Although the rebel forces in Hokkaidō surrendered, the government's response to the rebellion demonstrated the need for a strong centralized naval force. Even before the rebellion the restoration leaders had realized the need for greater political, economic and military centralization and by August 1869 most of the domains had returned their lands and population registers to the government. In 1871 the domains were abolished altogether and as with the political context the centralization of the navy began with the domains donating their forces to the central government. As a result, in 1871 Japan could finally boast a centrally controlled navy, this was also the institutional beginning of the Imperial Japanese Navy.

In February 1872, the Ministry of Military Affairs was replaced by a separate Army Ministry and Navy Ministry. In October 1873, Katsu Kaishū became Navy Minister.

Secondary Service (1872–1880)

After the consolidation of the government the new Meiji state set about to build up national strength, in the early period from 1868 many members of the Meiji coalition advocated preference of maritime forces over the army and saw naval strength as paramount. The Meiji government honored the treaties with the Western powers signed during the Bakumatsu period with the ultimate goal of revising them, leading to a subsided threat from the sea. This however led to conflict with disgruntled samurai who wanted to expel the westerners and groups which were opposed to the Meiji reforms, internal dissent including peasant uprisings become a greater concern for the government and as a result plans for naval expansion were curtailed.

In 1870, the new government drafted an ambitious plan to create a navy with 200 ships organized into ten fleets. It was abandoned within a year due to lack of resources. Financial considerations was also a major factor which restricted the growth of the navy during the 1870s. Japan at the time was not a wealthy state. Soon, however domestic rebellions, the Saga Rebellion (1874) and especially the Satsuma Rebellion (1877), forced the government to focus on land warfare and the army gained prominence. Naval policy, expressed by the slogan Shusei Kokubō (lit. "Static Defense"), focused on coastal defenses, and a standing army (established with the assistance of the second French Military Mission to Japan), and a coastal navy, leading to a military organization under the Rikushu Kaijū (Army first, Navy second) principle. The army gained the bulk of the military expenditures. During the 1870s and 1880s, the Imperial Japanese Navy remained an essentially coastal defense force, although the Meiji government continued to modernize it. Jo Sho Maru (soon renamed Ryūjō Maru) commissioned by Thomas Glover was launched at Aberdeen, Scotland on 27 March 1869.

British support and Influence

In 1870, an Imperial decree determined that Britain's Royal Navy should be the model for development, instead of the Netherlands. In 1873, a thirty-four-man British naval mission, headed by Lt. Comdr. Archibald Douglas, arrived in Japan. Douglas directed instruction at the Naval Academy at Tsukiji for several years, the mission remained in Japan until 1879, substantially advancing the development of the navy and firmly establishing British traditions within the Japanese navy from matters of seamanship to the style of its uniforms and the attitudes of its officers.

From September 1870, the English Lieutenant Horse, a former gunnery instructor for the Saga fief during the Bakumatsu period, was put in charge of gunnery practice on board the Ryūjō. In 1871, the ministry resolved to send 16 trainees abroad for training in naval sciences (14 to Great Britain, two to the United States), among which was Heihachirō Tōgō. A 34-member British naval mission visited Japan in 1873 for two years, headed by Commander Archibald Douglas. Later, Commander L.P. Willan was hired in 1879 to train naval cadets.

First interventions abroad (Taiwan 1874, Korea 1875–76)

During 1873, a plan to invade the Korean Peninsula, the Seikanron proposal made by Saigō Takamori, was narrowly abandoned by decision of the central government in Tokyo. In 1874, the Taiwan expedition was the first foray abroad of the new Imperial Japanese Navy and Army after the Mudan Incident of 1871, however the navy served largely as a transport force.

Various interventions in the Korean peninsula continued in 1875–1876, starting with the Ganghwa Island incident provoked by the Japanese gunboat Un'yō, leading to the dispatch of a large force of the Imperial Japanese Navy. As a result, the Japan–Korea Treaty of 1876 was signed, marking the official opening of Korea to foreign trade, and Japan's first example of Western-style interventionism and adoption of "unequal treaties" tactics.

In 1878, the Japanese cruiser Seiki sailed to Europe with an entirely Japanese crew.

Further modernization (1870s)

Ships such as the Fusō, Kongō and Hiei were built in British shipyards specifically for the Imperial Japanese Navy. Private construction companies such as Ishikawajima and Kawasaki also emerged around this time.

In 1883, two large warships were ordered from British shipyards. The Naniwa and Takachiho were 3,650 ton ships. They were capable of speeds up to 18 kn (33 km/h; 21 mph) and were armed with 54 to 76 mm (2 to 3 in) deck armor and two 260 mm (10 in) Krupp guns. The naval architect Sasō Sachū designed these on the line of the Elswick class of protected cruisers but with superior specifications. An arms race was taking place with China however, who equipped herself with two 7,335 ton German-built battleships (Ting Yüan and Chen-Yüan). Unable to confront the Chinese fleet with only two modern cruisers, Japan resorted to French assistance to build a large, modern fleet which could prevail in the upcoming conflict.

Influence of the French "Jeune École" (1880s)

During the 1880s, France took the lead in influence, due to its "Jeune École" ("young school") doctrine, favoring small, fast warships, especially cruisers and torpedo boats, against bigger units. The choice of France may also have been influenced by the Minister of the Navy, who happened to be Enomoto Takeaki at that time (Navy Minister 1880–1885), a former ally of the French during the Boshin War. Also, Japan was uneasy with being dependent on Great Britain, at a time when Great Britain was very close to China.

The Meiji government issued its First Naval Expansion bill in 1882, requiring the construction of 48 warships, of which 22 were to be torpedo boats. The naval successes of the French Navy against China in the Sino-French War of 1883–85 seemed to validate the potential of torpedo boats, an approach which was also attractive to the limited resources of Japan. In 1885, the new Navy slogan became Kaikoku Nippon (Jp:海国日本, "Maritime Japan").

In 1885, the leading French Navy engineer Émile Bertin was hired for four years to reinforce the Japanese Navy and to direct the construction of the arsenals of Kure and Sasebo. He developed the Sankeikan class of cruisers; three units featuring a single powerful main gun, the 320 mm (13 in) Canet gun. Altogether, Bertin supervised the building of more than 20 units. They helped establish the first true modern naval force of Japan. It allowed Japan to achieve mastery in the building of large units, since some of the ships were imported, and some others were built domestically at the arsenal of Yokosuka:

This period also allowed Japan "to embrace the revolutionary new technologies embodied in torpedoes, torpedo-boats and mines, of which the French at the time were probably the world's best exponents". Japan acquired its first torpedoes in 1884, and established a "Torpedo Training Center" at Yokosuka in 1886.

These ships, ordered during the fiscal years 1885 and 1886, were the last major orders placed with France. The unexplained sinking of Unebi en route from France to Japan in December 1886, created embarrassment however.

British shipbuilding

Japan turned again to Britain, with the order of a revolutionary torpedo boat, Kotaka which was considered the first effective design of a destroyer, in 1887 and with the purchase of Yoshino, built at the Armstrong works in Elswick, Newcastle upon Tyne, the fastest cruiser in the world at the time of her launch in 1892. In 1889, she ordered the Clyde-built Chiyoda, which defined the type for armored cruisers.

Between 1882 and 1918, ending with the visit of the French Military Mission to Japan, the Imperial Japanese Navy stopped relying on foreign instructors altogether. In 1886, she manufactured her own prismatic powder, and in 1892 one of her officers invented a powerful explosive, the Shimose powder.

Sino-Japanese War (1894–1895)

Japan continued the modernization of its navy, especially as China was also building a powerful modern fleet with foreign, especially German, assistance, and as a result tensions were building between the two countries over Korea. The Sino-Japanese war was officially declared on 1 August 1894, though some naval fighting had already taken place. A Japanese squadron had intercepted and defeated a Chinese force near Korea weeks before.

The Japanese Navy devastated Qing's Beiyang Fleet off the mouth of the Yalu River during the Battle of Yalu River on 17 September 1894, in which the Chinese fleet lost eight out of 12 warships. Although Japan turned out victorious, the two large German-made battleships of the Chinese Navy remained almost impervious to Japanese guns, highlighting the need for bigger capital ships in the Japanese Navy (Ting Yuan was finally sunk by torpedoes, and Chen Yuan was captured with little damage). The next step of the Imperial Japanese Navy's expansion would thus involve a combination of heavily armed large warships, with smaller and innovative offensive units permitting aggressive tactics.

As a result of the conflict, under the Treaty of Shimonoseki (April 17, 1895), Taiwan and the Pescadores Islands were transferred to Japan. The Imperial Japanese Navy took possession of the island and quelled opposition movements between March to October 1895, and the islands continued to be a Japanese colony until 1945. Japan also obtained the Liaodong Peninsula, although she was forced by Russia, Germany and France to return it to China (Triple Intervention), only to see Russia take possession of it soon after.

Suppression of the Boxer rebellion (1900)

The Imperial Japanese Navy further intervened in China in 1900 by participating, together with Western Powers, in the suppression of the Chinese Boxer Rebellion. The Navy supplied the largest number of warships (18 out of a total of 50) and delivered the largest contingent of troops among the intervening nations (20,840 Imperial Japanese Army and Navy soldiers, out of a total of 54,000).

The conflict allowed Japan to enter combat together with Western nations and to acquire first-hand understanding of their fighting methods.

Russo-Japanese War (1904–1905)

Following the Sino-Japanese War, and the humiliation of the forced return of the Liaotung peninsula to China under Russian pressure (the "Triple Intervention"), Japan began to build up its military strength in preparation for further confrontations. Japan promulgated a ¥215 million 10-year naval build-up program, under the slogan "Perseverance and determination" (臥薪嘗胆, Gashinshōtan), in which the Japanese commissioned 109 warships, for a total of 200,000 tons, and increased its Navy personnel from 15,100 to 40,800. The new fleet consisted of:

One of these battleships, Mikasa, among the most powerful warships afloat when completed, was ordered from the Vickers shipyard in the United Kingdom at the end of 1898, for delivery to Japan in 1902. Commercial shipbuilding in Japan was exhibited by construction of the twin screw steamer Aki-Maru, built for Nippon Yusen Kaisha by the Mitsubishi Dockyard & Engine Works, Nagasaki. The Imperial Japanese cruiser Chitose was built at the Union Iron Works in San Francisco, California.

These dispositions culminated with the Russo-Japanese War. At the Battle of Tsushima, Admiral Togo (flag in Mikasa) led the Japanese Combined Fleet into the decisive engagement of the war. The Russian fleet was almost completely annihilated: out of 38 Russian ships, 21 were sunk, seven captured, six disarmed, 4,545 Russian servicemen died and 6,106 were taken prisoner. On the other hand, the Japanese only lost 116 men and three torpedo boats. These victories broke Russian strength in East Asia, and triggered waves of mutinies in the Russian Navy at Sevastopol, Vladivostok and Kronstadt, peaking in June with the Potemkin uprising, thereby contributing to the Russian Revolution of 1905. The victory at Tsushima elevated the stature of the navy.

During the Russo-Japanese war, Japan also made frantic efforts to develop and construct a fleet of submarines. Submarines had only recently become operational military engines, and were considered to be special weapons of considerable potential. Naval losses for the Japanese Navy during the war amounted to two battleships, four cruisers, one armored cruiser, seven destroyers, and at least 10 torpedo boats; the majority of them were lost due to hitting Russian mines.

The Imperial Japanese Navy acquired its first submarines in 1905 from Electric Boat Company, barely four years after the U.S. Navy had commissioned its own first submarine, USS Holland. The ships were Holland designs and were developed under the supervision of Electric Boat's representative, Arthur L. Busch. These five submarines (known as Holland Type VII's) were shipped in kit form to Japan (October 1904) and then assembled at the Yokosuka, Kanagawa Yokosuka Naval Arsenal, to become hulls No.1 through 5, and became operational at the end of 1905.

Towards an autonomous national navy (1905–1914)

Japan continued in its efforts to build up a strong national naval industry. Following a strategy of "copy, improve, innovate", foreign ships of various designs were usually analysed in depth, their specifications often improved on, and then were purchased in pairs so as to organize comparative testing and improvements. Over the years, the importation of whole classes of ships was progressively substituted by local assembly, and then complete local production, starting with the smallest ships, such as torpedo boats and cruisers in the 1880s, to finish with whole battleships in the early 20th century. The last major purchase was in 1913 when the battlecruiser Kongō was purchased from the Vickers shipyard. By 1918, there was no aspect of shipbuilding technology where Japanese capabilities fell significantly below world standards.

The period immediately after Tsushima also saw the IJN, under the influence of the navalist theoretician Satō Tetsutarō, adopt an explicit policy of building for a potential future conflict against the United States Navy. Satō called for a battlefleet at least 70% as strong as that of the USA. In 1907, the official policy of the Navy became an 'eight-eight fleet' of eight modern battleships and eight battlecruisers. However, financial constraints prevented this ideal ever becoming a reality.

By 1920, the Imperial Japanese Navy was the world's third largest navy and a leader in naval development:

World War I (1914–1918)

Japan entered World War I on the side of the Entente, against Germany and Austria-Hungary, as a consequence of the 1902 Anglo-Japanese Alliance.

In the Siege of Tsingtao, the Japanese Navy helped seize the German colony of Tsingtao. During the siege, beginning on 5 September 1914, Wakamiya conducted the world's first successful sea-launched air strikes. On 6 September 1914, in the very first air-sea battle in history, a Farman aircraft launched by Wakamiya attacked the Austro-Hungarian cruiser Kaiserin Elisabeth and the German gunboat Jaguar off Tsingtao. from Kiaochow Bay. Four Maurice Farman seaplanes bombarded German land targets like communication and command centers, and damaged a German minelayer in the Tsingtao peninsula from September to 6 November 1914 when the Germans surrendered.

A battle group was also sent to the central Pacific in August and September to pursue the German East Asiatic squadron, which then moved into the Southern Atlantic, where it encountered British naval forces and was destroyed at the Battle of the Falkland Islands. Japan seized former German possessions in northern Micronesia, which remained Japanese colonies until the end of World War II, under the League of Nations' South Pacific Mandate.

Hard pressed in Europe, where she had only a narrow margin of superiority against Germany, Britain had requested, but was denied, the loan of Japan's four newest Kongō-class battlecruisers (Kongō, Hiei, Haruna, and Kirishima), some of the first ships in the world to be equipped with 356 mm (14 in) guns, and the most formidable battlecruisers in the world at the time.

Following a further request by the British and the initiation of unrestricted submarine warfare by Germany the Japanese, in March 1917, sent a special force of destroyers to the Mediterranean. This force, consisting of one armoured cruiser, Akashi as flotilla leader and eight of the Navy's newest destroyers (Ume, Kusunoki, Kaede, Katsura, Kashiwa, Matsu, Sugi, and Sakaki), under Admiral Satō Kōzō, was based in Malta and efficiently protected allied shipping between Marseille, Taranto, and ports in Egypt until the end of the War. In June, Akashi was replaced by Izumo, and four more destroyers were added (Kashi, Hinoki, Momo, and Yanagi). They were later joined by the cruiser Nisshin. By the end of the war, the Japanese had escorted 788 allied transports. One destroyer, Sakaki, was torpedoed on 11 June 1917 by a German submarine with the loss of 59 officers and men. A memorial at the Kalkara Naval Cemetery in Malta was dedicated to the 72 Japanese sailors who died in action during the Mediterranean convoy patrols.

In 1917, Japan exported 12 Arabe-class destroyers to France.

In 1918, ships such as Azuma were assigned to convoy escort in the Indian Ocean between Singapore and the Suez Canal as part of Japan’s contribution to the war effort under the Anglo-Japanese alliance.

After the conflict, the Japanese Navy received seven German submarines as spoils of war, which were brought to Japan and analysed, contributing greatly to the development of the Japanese submarine industry.

Interwar years (1918–1937)

In the years before World War II, the IJN began to structure itself specifically to fight the United States. A long stretch of militaristic expansion and the start of the Second Sino-Japanese War in 1937 had exacerbated tensions with the United States, which was seen as a rival of Japan.

This was in conflict with Japan's doctrine of "decisive battle" (艦隊決戦, Kantai kessen, which did not require long range), in which IJN would allow the U.S. to sail across the Pacific, using submarines to damage it, then engage the U.S. Navy in a "decisive battle area", near Japan, after inflicting such attrition. This is in keeping with the theory of Alfred T. Mahan, to which every major navy subscribed before World War II, in which wars would be decided by engagements between opposing surface fleets (as they had been for over 300 years). Following the dictates of Satō (who doubtless was influenced by Mahan), it was the basis for Japan's demand for a 70% ratio (10:10:7) at the Washington Naval Conference, which would give Japan superiority in the "decisive battle area", and the U.S.' insistence on a 60% ratio, which meant parity. Japan, unlike other navies, clung to it even after it had been demonstrated to be obsolete.

It was also in conflict with her past experience. Japan's numerical and industrial inferiority led her to seek technical superiority (fewer, but faster, more powerful ships), qualitative superiority (better training), and aggressive tactics (daring and speedy attacks overwhelming the enemy, a recipe for success in her previous conflicts), but failed to take account of any of these traits. She failed to take account of the fact her opponents in the Pacific War did not face the political and geographical constraints of her previous wars, nor did she allow for losses in ships and crews.

Between the wars, Japan took the lead in many areas of warship development:

By 1921, Japan's naval expenditure reached nearly 32% of the national budget. In 1941, the Imperial Japanese Navy possessed 10 battleships, 10 aircraft carriers, 38 cruisers (heavy and light), 112 destroyers, 65 submarines, and various auxiliary ships.

Japan at times continued to solicit foreign expertise in areas in which the IJN was inexperienced, such as naval aviation. In 1918, Japan invited the French military mission to Japan (1918–19), composed of 50 members and equipped with several of the newest types of airplanes to establish the fundamentals of Japanese naval aviation (the planes were several Salmson 2A2, Nieuport, Spad XIII, two Breguet XIV, as well as Caquot dirigibles). In 1921, Japan hosted for a year and a half the Sempill Mission, a group of British instructors who were able to train and advise the Imperial Japanese Navy on several new aircraft such as the Gloster Sparrowhawk, and on various techniques such as torpedo bombing and flight control.

During the pre-war years, two schools of thought battled over whether the navy should be organized around powerful battleships, ultimately able to defeat American ones in Japanese waters, or around aircraft carriers. Neither really prevailed, and both lines of ships were developed, with the result neither solution displayed overwhelming strength over the American adversary. A consistent weakness of Japanese warship development was the tendency to incorporate too much armament, and too much engine power, in comparison to ship size (a side-effect of the Washington Treaty), leading to shortcomings in stability, protection and structural strength.

The Imperial Japanese Navy was faced, before and during World War II, with considerable challenges, probably more so than any other navy in the world. Japan, like Britain, was almost entirely dependent on foreign resources to supply its economy. To achieve Japan’s expansionist policies, IJN had to secure and protect distant sources of raw material (especially Southeast Asian oil and raw materials), controlled by foreign countries (Britain, France, and the Netherlands). To achieve this goal, she had to build large warships capable of long range assault.

World War II

In order to combat the numerically superior American navy, the IJN devoted large amounts of resources to creating a force superior in quality, the objective being of "making up for quantity by means of quality". Betting on the agile success of aggressive tactics which stemmed from Mahanian doctrine and the concept of decisive battle, Japan did not invest significantly in capabilities needed to protect its long shipping lines against enemy submarines, particularly under-investing in the vital area of antisubmarine warfare (both escort ships and escort carriers), and in the specialized training and organization to support it. Imperial Japan's reluctance to use its submarine fleet for commerce raiding and failure to secure its communications also hastened its defeat.

During the first six months of the Pacific War, the IJN enjoyed spectacular success inflicting heavy defeats on Allied forces. The attack on Pearl Harbor crippled the battle line of the US Pacific fleet while Allied navies were devastated during the conquest of Southeast Asia. Japanese naval aircraft were also responsible for the sinkings of the Prince of Wales and Repulse which was the first time that capital ships were sunk by aerial attack while underway. In April 1942, the Indian Ocean raid drove the Royal Navy from South East Asia.

After these successes, the IJN now concentrated on the elimination and neutralization of strategic points from where the Allies could launch counteroffensives against Japanese conquests. However, at Coral Sea the Japanese were forced to abandon their attempts to isolate Australia while the defeat in the Midway Campaign saw the Japanese forced on the defensive. The campaign in the Solomon Islands, in which the Japanese lost the war of attrition, was the most decisive; the Japanese failed to commit enough forces in sufficient time. During 1943 the Allies were able to reorganize their forces and American industrial strength began to turn the tide of the war. American forces ultimately managed to gain the upper hand through a vastly greater industrial output and a modernization of its air and naval forces.

In 1943, the Japanese also turned their attention to the defensive perimeters of their previous conquests. Forces on Japanese held islands in Micronesia were to absorb and wear down an expected American counteroffensive. However, American industrial power become apparent and the military forces that faced the Japanese in 1943 were overwhelming in firepower and equipment. From the end of 1943 to 1944 Japan's defensive perimeter failed to hold.

Defeat at the Philippine Sea was a disaster for Japanese naval air power with American pilots terming the slanted air/sea battle the Great Marianas Turkey Shoot, mostly going in the favor of the U.S., while the battle of Leyte Gulf led to the destruction of a large part of the surface fleet. During the last phase of the war, the Imperial Japanese Navy resorted to a series of desperate measures, including a variety of Special Attack Units which were popularly called kamikaze. By May 1945, most of the Imperial Japanese Navy had been sunk and the remnants had taken refuge in Japan's harbors. By July 1945, all but one of the Imperial Japanese Navy capital ships had been sunk in raids by the United States Navy.

Self-Defense Forces

Following Japan's surrender and subsequent occupation by the Allies at the conclusion of World War II, the Imperial Japanese Navy was dissolved in 1945. In the new constitution of Japan which was drawn up in 1947, Article 9 specifies that "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." The prevalent view in Japan is that this article allows for military forces to be kept for the purposes of self-defense.

In 1952, the Coastal Safety Force was formed within the Maritime Safety Agency, incorporating the minesweeping fleet and other military vessels, mainly destroyers, given by the United States. In 1954, the Coastal Safety Force was separated, and the JMSDF was formally created as the naval branch of the Japanese Self-Defense Force (JSDF), following the passage of the 1954 Self-Defense Forces Law. Japan's current navy falls under the umbrella of the Japan Self-Defense Forces (JSDF) as the Japan Maritime Self-Defense Force (JMSDF).

Personnel scale of promotions

Prior to the Second World War, the three grades of seaman were third, second and first class. Petty officers were selected from among the first-class seamen, and were likewise graded from the third through the first classes. After a certain period, a first-class petty officer would be eligible for promotion to warrant officer. After five years of meritorious service as a warrant officer, he could be commissioned as a special-service officer in the rank of second (acting) sub-lieutenant. Such special-service officers could rise to the rank of special-service lieutenant-commander, or possibly even higher.

The majority of IJN officers were educated at and commissioned from the Imperial Naval Academy at Etajima. After passing out, line officers would receive further training at the Naval College, while those in a specialised branch (engineers, paymasters and fleet medical officers) would be sent to their respective college (Engineering, Intendants School and Surgery School). Graduates of universities or higher technical schools could also receive direct commissions as special-service officers in the non-combatant branches.

The promotion of officers in the IJN was by selection, with special promotions made at the discretion of a board of admirals. In peacetime, all officers passed out from Etajima as midshipmen, after which they would serve aboard a training ship for around a year. At the end of this period, they would receive commissions as second (acting) sub-lieutenants and enter either the Torpedo or Gunnery schools. After another 18 months, six of which would be spent in either the Torpedo or Gunnery Schools, they would be promoted to sub-lieutenants and serve as junior officers aboard a ship for a prescribed time. Following this, they would enter an advanced torpedo or gunnery programme and receive promotion to lieutenant two years after their promotion to sub-lieutenant. Line-service lieutenants of over four years in the service, including enrollment in programmes at the Naval War College (or a specialised higher school for those in non-executive branches), would typically be promoted to the rank of lieutenant-commander. For special-service midshipmen, promotion to second sub-lieutenant came after two years of service and after three years for the rank of sub-lieutenant. Special-service officers could be promoted to the rank of lieutenant-commander by special appointment.

After the rank of lieutenant-commander, promotion was highly competitive and solely by selection. Promotions to the ranks of commander through rear-admiral were typically scheduled in two-year intervals, though in practice, promotions to commander were made after five years at the rank of lieutenant-commander and promotions to captain made after four years as a commander. Promotions to rear-admiral usually came after five to six years as a captain, with promotions to vice-admiral coming after three years in the rank of rear-admiral. During wartime, promotion time limits were reduced by half. In general, vice-admiral was the highest regular rank an officer could achieve in the IJN. Promotion to the rank of full admiral was by direct Imperial appointment only, and came only to vice-admirals after long service or to those recognised for special merits. The ceremonial rank of marshal-admiral (fleet admiral) was also only by direct Imperial appointment, more in the nature of a special award than a substantive rank.

Posthumous promotions and commissions were also common, typically coming after the officer or sailor had been killed in action or had died after a long and distinguished career.