World War II: Japan Summary

  • Last updated on November 11, 2022

The core of Japan’s military institution, the Imperial Japanese Army, began its ascendancy to political dominance in the 1930’s.

Political Considerations

The core of Japan’s military institution, the Imperial Japanese ArmyImperial Japanese Army, began its ascendancy to political dominance in the 1930’s. Through the intimidation and, often, the assassination of its political opponents, the military succeeded in controlling the inner circle of advisers to the Japanese emperor, HirohitoHirohito (emperor of Japan)Hirohito (1901-1989). The army, citing its loyalty to the emperor, subscribed to a theory of preparation for total war and devised a master plan that sought to make Japan the primary political power in Asia and the Pacific.World War II (1939-1945)[World War 02];JapanWorld War II (1939-1945)[World War 02];JapanJapan;World War II[World War 02]

The ManchuriaJapanese Kwantung Kwantung ArmyArmy, which, following World War I, had occupied bases in Manchuria by treaty with the China;war with Japan[Japan]Japan;vs. China[China]Chinese, provoked a confrontation with local Chinese authorities there and launched a series of military strikes that ended with the occupation of Manchuria in 1931. Sino-Japanese War, Second (1937-1945)[Sino Japanese War, Second]Six years later, in the vicinity of the Marco Polo Bridge near Beijing, the Japanese alleged an attack by elements of the Chinese Nationalist Army and launched a campaign of full-scale warfare against China in an attempt to dominate, control, and occupy much of the country.

The U.S. government, together with a number of Western European nations, sought to oppose the Japanese expansion. These nations launched an economic Embargo of Japan (1930’s)embargo seeking to limit the growth of Japanese military and naval power. Because Japan lacked many of the natural resources needed to produce the supplies and equipment required to fuel a powerful military machine, these restrictions prompted the more aggressive elements in the Japanese army to press for an all-out war against the United States and its European supporters, mainly the British, Dutch, and French, all of whom had colonies on both the South Asian continent and the islands situated off it. In September, 1939, the Japanese, seeking to counteract the power of the Allied nations, signed the Tripartite Pact (1939)Tripartite Pact with Germany and Italy, allying itself with those two Fascist nations in their confrontation with France and England.

In 1940 Japan had established bases in French Indochina;Japanese invasionIndochina–the present-day countries of Vietnam;Japanese inVietnam, LaosLaos, and Cambodia;Japanese inCambodia. On December 7, 1941, the Japanese launched a surprise attack on the American naval base at Pearl Harbor attack (1941)Pearl Harbor, in Hawaii, while at the same time invading the Philippines;Japanese invasionPhilippines and the Malayan CampaignMalay Peninsula. The Japanese forces then attacked the Dutch East Indies, Japanese invasion ofDutch East Indies, which they seized for its critical oil fields.

Military Achievement

The World War II[World War 02];Pacific theaterinitial attacks by Japan’s armies and navy proved to be spectacularly successful. The task force that attacked Pearl Harbor consisted of six aircraft carriers with 183 planes aboard and supporting vessels. This force wreaked havoc on the unprepared American fleet tied up at the base. The Americans lost or suffered severe damage to eighteen warships. Some 2,335 sailors were killed, and an additional 1,178 were wounded. The Japanese lost only twenty-nine aircraft and fifty-five flyers in the attack. The Imperial fleet returned to home base with no loss to its surface units.

The isolated Central Pacific U.S. bases at Guam and Wake Island fell quickly to the Japanese, who also occupied both Kiska and Attu, in Alaska’s Aleutian Island chain, forestalling any move by the United States to use the Aleutians as a base in a retaliatory attack.

The Imperial Japanese ArmyImperial Japanese Army also enjoyed a series of quick successes in its campaigns in the Philippine Islands, the Malay Peninsula, and the Dutch East Indies. Although the Americans put up spirited defenses on Luzon’s Bataan Philippines;Japanese invasionPeninsula and Corregidor, by April 9, 1942, the Japanese had secured control of the Philippines. General Douglas MacArthur, DouglasMacArthur, DouglasMacArthur (1880-1964), commanding the combined American and Filipino forces, had received his orders to leave for Australia before the actual fall of the Philippines. President Franklin D. Roosevelt, Franklin D.Roosevelt, Franklin D.Roosevelt (1882-1945) and the Allies needed him to prepare that continent against attack in the event that the Japanese moved in that direction.

The British defense of Malayan CampaignMalaya and Singapore proved to be even more disastrous. Despite numerical superiority, the British were no match for the Japanese infantry, whose units included the best of the Imperial Japanese Army. By February 15, 1942, Japan had captured Singapore, gaining control of the entire Malay Peninsula.

The Japanese had advanced into both Burma and the Dutch East Dutch East Indies, Japanese invasion ofIndies as well, ensuring the island empire’s supply of both rice and oil. In fewer than one hundred days, the Japanese military had accomplished all of the goals originally established by Imperial General Staff.

The euphoria of these early Japanese victories had disappeared by mid-1942. Their advance in the Pacific islands was far less successful. In April of that year, U.S. B-25 B-25 bomber[B 25 bomber]bombers flew off a carrier to conduct a raid on the cities of Tokyo, Yokohama, Kobe, and Nagoya. Moreover, the Americans turned back Japanese invasion fleets intent on taking all of New Guinea to the south and Midway, Battle of (1942)Midway, formerly Brooks Islands, to the east. In the latter battle, a turning point in the war, the Japanese lost four virtually irreplaceable aircraft carriers and some of their best naval aviators. General MacArthur then began a campaign to recover all of New Guinea and to take back the Philippines. This action by the Americans ended the threat of Japanese invasion of Australia.

Simultaneously, the U.S. Navy began a series of attacks on Japanese island bases in the Pacific theater (World War II)World War II (1939-1945)[World War 02];Pacific theatermid-Pacific: the Gilbert Islands, the Marshall Islands, the Mariana Islands, and the Caroline Islands. One by one, these critical outposts fell to the U.S. Navy and U.S. Marines, leaving Japan open to both direct air attack and the threat of the ultimate invasion of the home islands themselves.

By August, 1945, U.S. military forces had succeeded in reconquering all of the Pacific bases previously seized by the Japanese. They had even captured the island of Okinawa (1944-1945)Okinawa, the key Japanese base in the Ryukyu Island chain, only 380 miles south of Kyūshū, one of the Japanese home islands. The U.S. forces had also severed Japan’s supply lines to the south, depriving the Japanese of raw materials, such as oil, that were critical to their ability to continue the war. The ultimate weapons in the U.S. attack proved to be the two atomic Atomic bomb;World War II[World War 02]bombings of the cities of Hiroshima, JapanHiroshima and Nagasaki, JapanNagasaki, which forced Hirohito to surrender.

Weapons, Uniforms, and Armor

During Armor;JapaneseUniforms;Japanesethe late 1930’s, the Japanese government built a powerful military and naval machine. Its infantry, artillery, and air forces acquired extensive experience in Manchuria and in their invasion of China. The Imperial Japanese Imperial Japanese ArmyArmy relied heavily upon a well-trained, mobile, and aggressive infantry that was trained and skilled in hand-to-hand combat. During the Malayan Campaign, for example, the British forces with their motorized equipment were handicapped by narrow roads through the heavy jungle. The Japanese infantry mounted bicycles to navigate the landscape, riding on the wheel rims when they blew tires and shouldering their bicycles to ford rivers.

World War II: Japan and the Pacific Theater

The enlisted man in the Japanese army was dressed poorly. He seldom shaved and wore a patched uniform with unpolished boots and insignia. He was poorly armed, with only a rifle and a bayonet. He walked rather than marched. Extremely fit, he covered surprising distances.

The quality of the machine Machine guns;Japaneseguns available to the Japanese infantry remained marginal, especially since infantry tactics counted on heavy machine-gun support. Japanese tank and artillery support fell far below the level of that of their enemies. Tanks;JapaneseTanks operated more in the capacity of armored personnel carriers than of powerful mobile heavy weapons. Artillery had proven unnecessary in the Chinese campaign, mainly because the Chinese themselves lacked formidable artillery support. The situation changed radically when the Japanese forces had to fight against heavily armed U.S. land and sea forces.

The Japanese air Air forces;Japaneseforces depended primarily on their speedy, highly maneuverable Mitsubishi A6M2 Zero Zero fightersfighters. Early in the war these aircraft dominated the skies over China, the Dutch East Indies, and the Philippines. Opposing pilots could not match the Zero’s speed. The Zero fighters, flown by skilled and highly trained pilots, dominated the opposition. Although the plane proved to be mechanically superior to those of Japan’s opponents, it was never modified in any meaningful way from its initial model. As the war progressed, the U.S. aircraft industry began to turn out planes that were both faster and better equipped than the Zero. The Japanese plane’s lack of armor also resulted in a higher mortality rate among its corps of pilots. Another, often fatal, flaw lay in the plane’s lack of self-sealing fuel tanks. The Japanese bomber fleet suffered even more from a lack of sufficient armor. The bombers, handicapped by slow speed as well as the vulnerable fuel tanks, found themselves easy targets for Allied pursuit aircraft.

The Japan;navyNavies;JapanJapanese navy built a formidable naval force centered around several super-Battleships;Japanesebattleships of the Yamato shipsYamato class, the largest vessels of that category ever built. However, these capital ships played no meaningful role in the naval battles that occurred after the American navy recovered from the Pearl Harbor attack. Most naval authorities suggest that Japan might have been more successful had it instead built more aircraft carriers, because these ships proved to play a critical role in the naval warfare of World War II. The Imperial Japanese Navy lost many of its carriers early in the war, in May, 1942, at the Coral Sea, Battle of the (1942)Battle of the Coral Sea, but more important at the Battle of Midway from June 3-6. Japanese industry was unable to build replacements quickly enough to keep up with its opposition. The Japanese also lacked a sufficient number of support vessels, especially for the transport of critical supplies, such as oil from the Dutch East Indies.

On May 11, 1945, in the Pacific theater, two Japanese kamikaze pilots directed their aircraft into the USS Bunker Hill off Kyushu.


The Japanese Submarines;World War II[World War 02]Submarines;Japanesesubmarine fleet did not conduct long-range raiding campaigns on U.S. shipping, as did the German fleet in the Atlantic Ocean. More often it operated either as part of larger fleet units or as supply ships for the army’s increasingly isolated Pacific island bases. Submarines;U.S.U.S. submarines, in contrast, preyed constantly upon the limited number of Japanese merchant ships and the extended supply lines on which Japan depended to move materials to its home islands.

Military Organization

Japan had, by 1940, become a Totalitarianism;Japantotalitarian nation. The military, utilizing Hirohito as a symbol, had organized Japanese society into a cohesive body dedicated to the worship of the emperor and total obedience to a government dominated by the leaders of the Japanese Imperial Army and Navy. Civilian diplomats, including the country’s prime minister, served only to cover the aggressive planning of the military factions. Japanese industry no longer operated as a competitive economic entity in the world market, as manufacturers subordinated themselves to government control and dedicated themselves to meeting the needs of the armed forces.

The war in China had, however, decimated both Japan’s manpower and its resources. By mid-1941 Japan had already lost 185,000 soldiers, and peace in China remained elusive to Japanese planners. The Japanese High CommandJapanese High Command, however, insisted on the empire’s expansion to provide the raw material necessary for the growth of Japan as a major global power.

One critical factor continued to plague the military hierarchy throughout the 1930’s and 1940’s: An intense rivalry existed between the army and navy Japan;army vs. navyfactions. Each force had its own assessment of the direction the armed forces should take, and they quarreled constantly over the country’s military priorities.

The Japanese army saw Japan’s major long-term enemy to be the Soviet Soviet Union;Japanese perceptionUnion and its implied threat of a communist world revolution and sought to concentrate the empire’s resources on a continuing buildup of its ground forces and support troops on the Asian mainland itself. The army saw the European colonies on the continent’s southern boundaries as the solution to its needs for basic commodities to strengthen its military capabilities. It was prepared to go to war with the United States only if that country denied Japan the raw materials necessary to create and maintain a self-sufficient empire.

The Japanese navy saw the United United States;relations with Japan[Japan]Japan;U.S. relationsStates as Japan’s primary threat. It recognized the potential of the powerful American Naval power;U.S. in World War IIfleet, with its capabilities for a wide range of operations throughout the Pacific, its virtually unlimited supply of fuel, and its shipyard construction capacity. The navy sought to increase substantially its number of capital ships in order to confront the American navy on an equal basis. It preferred to postpone any conflict with the United States until Japan was strong enough to meet the U.S. fleet on equal terms.

Admiral Isoroku Yamamoto, IsorokuYamamoto, IsorokuYamamoto (1884-1943), commander in chief of the Imperial Navy’s combined fleet at the time of the attack on Pearl Harbor, was not carried away by the success of the raid. He believed that his country would have to force the United States to sue for peace within six months of the attack or the opportunity for a successful outcome of the conflict would be lost. Subsequent events proved him correct: After suffering initial reverses, the United States rebounded to seize control and, ultimately, to win the conflict.

Both arms of the Japanese military maintained their own separate air forces, as did those of the United States. However, the U.S. Army and Navy generally cooperated, with joint strategies. The Japanese army and navy did not; the two arms operated individually, often without effective communication. For example, in December, 1941, during the first naval attack on Clark Field in the Philippines, Japanese army bombers flew into the path of the incoming naval aircraft conducting an assault of the field.

On occasion the two separate air arms deliberately withheld critical information from each other. At Nagoya’s Mitsubishi factory, workers strung a curtain between projects separately assigned to the site by the army and navy, thus preventing an interchange of ideas between the two groups. Throughout the war the army and navy took turns condemning the other for operational failures.

Doctrine, Strategy, and Tactics

Both the Japanese army and navy adopted the warrior code of Bushidō (Japanese warrior code)bushidō as a way of life. This philosophy came to be defined as one of absolute loyalty to the emperor and of bravery, frugality, simplicity, and unhesitating sacrifice. The military government sought to indoctrinate the people of Japan with the same spirit of self-sacrifice. The island nation’s enemies came to realize that Japanese soldiers, sailors, and even civilians would fight to the death and would rather die than surrender. In battle after battle, despite overwhelming evidence that further conflict was useless, Japanese soldiers fought until killed by the enemy. Only at the very end of the war, on Okinawa, did numerous members of the Imperial Japanese Army surrender.

The tail section of a Japanese Suisei aircraft on the deck of the USS Kitkun Bay after exploding over the ship.

(U.S. Navy)

The officer caste demonstrated an even greater degree of commitment to bushidō. When faced with certain defeat, many officers chose to commit Suicide;JapanSeppuku (ritual suicide)seppuku, or ritual suicide, by disemboweling themselves, a practice also known as Hara-kiri[harakiri]hara-kiri. If time did not permit, they ordered their aides to dispatch them with a pistol shot to the head.

In late 1944 in the Philippines, and later during the Okinawa (1944-1945)Battle of Okinawa, the Japanese army and navy air forces began to organize a special attack corps called the Kamikaze corpsKamikaze, (kamikaze means “divine wind”). The name recalled a typhoon that struck the Japanese home islands in 1281, destroying a Mongol fleet invading from the Asian mainland and saving the island nation. The flyers of the Kamikaze Special Attack Corps deliberately rammed their aircraft into Allied naval vessels, at formidable cost to the ships and men serving aboard them.

Japanese officer candidates began at the age of fourteen as recruits in military prep schools. At seventeen, promising aspirants transferred to a more advanced preparatory school in Tokyo, where their real training began. Future officers completed their schooling at the military academy in Military education;JapanIchigaya. Subjected to constant heavy indoctrination, they adopted the concept of “a will which knows no defeat.” Their mentors emphasized physical conditioning and discouraged independent thinking. Future officers were expected to subscribe fully to the Bushidō (Japanese warrior code)bushidō code. They, in turn, demanded the same obedience to orders from the enlisted personnel under them.

Throughout the many battles for the islands of the Pacific, the sites were secured by invading U.S. soldiers only after every last Japanese fighter was killed. On Saipan and Okinawa, Japanese civilians, both men and women, joined the doomed soldiers in the final conflict. In the case of Okinawa, 150,000 civilians, one-third of the island’s population, died following the U.S. invasion, often accompanying and aiding soldiers and sailors of the Imperial Army and Navy.

The bushidō code had its dark side. By Western standards Japanese army and navy units engaged in substantial violations of human rights in their contact with civilian populations in conquered lands and with captured military prisoners. After seizing the city of Nanjing, Rape of (1937-1938)Nanjing from Chinese forces in 1937, the Imperial Japanese Army ran amok, slaughtering an estimated 250,000 of the city’s civilian population. Tens of thousands of Chinese civilians were also massacred in Singapore soon after the Japanese capture of the city.

In another example of contempt for those who chose to surrender, during the so-called Bataan Death March Bataan Death March (1942)(1942) Japanese soldiers killed thousands of Prisoners of war;World War II[World War 02]captured American and Filipino troops suffering from illness and exhaustion. After their surrender some of the weakened and starving prisoners had failed to keep pace with the march to prison camps ordered by their conquerors. Those who fell behind were summarily shot or beaten to death. A similar series of atrocities took place on the Burma-Siam Railroad[Burma Siam Railroad]Burma-Siam Railroad, and in the Sandakan Death MarchSandakan Death March. In these cases and in many others, the Japanese failed to recognize the precepts of the Geneva Geneva Conventions;JapanConventions as they applied to the humane treatment of prisoners of war.

The overall strategy of the Japanese military counted on the capture of critical Southeast Asia;World War II[World War 02]Southeast Asian areas that were rich in resources. Once secured, the army was prepared to hold these bases tenaciously, while the navy protected the seas around them. The Japanese High CommandJapanese High Command expected the troops in the field to resist to the last man any forces seeking to dislodge them. Unfortunately for the Japanese strategists, Japan lost both air and sea supremacy as the war continued. The island bastions fell one by one. Finally, Atomic bomb;World War II[World War 02]U.S. forces dropped atom bombs on cities in the home islands, which the Japanese could no longer successfully defend.

Tactically the Japanese military depended on the tenacity of its Infantry;Japaneseinfantry, termed by the military Propaganda;Japanesepropaganda as “men of spirit.” Adopting this concept, the infantry followed a pattern of aggressive offensive tactics. Convinced of his superior physical conditioning, the Japanese soldier sought to close with the enemy and engage in hand-to-hand combat, often in nighttime sneak attacks. The military planners designed this approach to terrify their opponents.

With the use of Kamikaze corpsKamikaze air and sea formations, the Japanese High Command believed it could exact such fearful losses on U.S. naval and civilian shipping that the United States would refrain from trying to invade the Japanese home islands. Even after the Japanese armed forces lost their ability to stop the advancing Allied armies, they prepared to give up their lives rather than surrender. This Japanese commitment to self-destruction, as well as the potential loss of both American and Japanese civilian lives, motivated U.S. president Truman, Harry S.Truman, Harry S.Harry S. Truman (1884-1972) to use atomic Atomic bomb;World War II[World War 02]bombs on Hiroshima and Nagasaki in order to convince Japanese emperor Hirohito to surrender his nation.

Contemporary Sources

English translations of Japanese texts actually written during World War II are rare. Some insight into the Japanese thinking at the time can be found in Sakamaki, Paul S.Sakamaki, Paul S.Paul S. Sakamaki’s I Attacked Pearl Harbor (1949) and in Hasegawa, NyozekanHasegawa, Nyozekan Nyozekan Hasegawa’s The Japanese Character (1966), which contains a collection of essays written between 1935 and 1938. There were also a few other autobiographical works, such as Hino, AshiheiHino, Ashihei Ashihei Hino’s War and Soldier (1940) and Nagatsuka, R.Nagatsuka, R. R. Nagatsuka’s I Was a Kamikaze (1973). Tsuji, MasanobuTsuji, Masanobu Masanobu Tsuji’s Singapore: The Japanese Version (1960) remains one of the few accounts in English by an officer involved in planning the Pacific war. During the 1930’s, the Japanese published a large number of propaganda magazines, such as Contemporary Japan, that include details on the military but that tried to portray Japan as suffering from the depredations of other countries.

The best contemporary American source of information on Japanese thinking and action can be found in Benedict, RuthBenedict, RuthRuth Benedict’s The Chrysanthemum and the Sword (1946). A cultural anthropologist, Benedict presented a graphic analysis of Japanese thinking and customs at the time of World War II. One chapter of her book contains a specific analysis of the thinking of the Japanese military.

The writings of American military personnel found in government reports and military journals also furnish a Western analysis of Japanese military activity. Among these are The Japanese Story of the Battle of Midway (1947), compiled by the U.S. Office of Naval Intelligence and published by the U.S. Government Printing Office. There are also official histories by the British, such as Kirby, S. WoodburnKirby, S. Woodburn S. Woodburn Kirby’s The War Against Japan (5 volumes, from 1957), and by the Australians, starting with Wigmore, LionelWigmore, Lionel Lionel Wigmore’s The Japanese Thrust (1957).World War II (1939-1945)[World War 02];JapanJapan;World War II[World War 02]

Books and Articles
  • Agawa, Hiroyuki. The Reluctant Admiral: Yamamoto and the Imperial Navy. Tokyo: Kodansha International, 1979.
  • Allen, Thomas B., and Norman Polmar. Code-Name Downfall: The Secret Plan to Invade Japan and Why Truman Dropped the Bomb. New York: Simon and Schuster, 1995.
  • Astor, Gerald. Operation Iceberg: The Invasion and Conquest of Okinawa in World War II. New York: Dell, 1995.
  • Goldstein, David M., and Katherine V. Dillon, eds. Fading Victory: The Diary of Admiral Matome Ugaki, 1941-1945. Pittsburgh, Pa.: University of Pittsburgh Press, 1991.
  • Harries, Meirion, and Susie Harries. Soldiers of the Sun: The Rise and Fall of the Imperial Japanese Army. New York: Random House, 1991.
  • Jones, Don. Oba, the Last Samurai: Saipan, 1944-1945. Novato, Calif.: Presidio Press, 1986.
  • Jowett, Philip. The Japanese Army, 1933-45: 1931-42. New York: Osprey, 2002.
  • _______. The Japanese Army, 1933-45: 1942-45. New York: Osprey, 2002.
  • Rottman, Gordon L. Japanese Army in World War II: Conquest of the Pacific, 1941-42. New York: Osprey, 2005.
  • _______. Japanese Army in World War II: The South Pacific and New Guinea, 1942-43. New York: Osprey, 2005.
  • Sakai, Saburo. Samurai! New York: Pocket Books, 1996.
  • Sakaida, Henry. Imperial Japanese Navy Aces, 1937-45. New York: Osprey, 1998.
  • _______. Japanese Army Air Force Aces, 1937-45. New York: Osprey, 1997.
  • Taaffe, Stephen R. MacArthur’s Jungle War: The 1944 New Guinea Campaign. Lawrence: University Press of Kansas, 1998.
  • Yahara, Hiromichi. The Battle for Okinawa. New York: John Wiley and Sons, 1995.
Films and Other Media
  • Enola Gay and the Bombing of Japan. Documentary. Brookside Media, 1995.
  • Kamikaze: Death from the Sky. Documentary. MPI Home Video, 1989.
  • Letters from Iwo Jima. Feature film. Malpaso/Amblin, 2006.
  • Okinawa: The Final Battle. Documentary. History Channel, 1996.
  • Pearl Harbor: Two Hours That Changed the World. Documentary. ABC, 1991.
  • Survivors. Documentary. Steven Okazaki, 1982.
  • The World at War. Documentary. Thames Television, 1973.

World War II: United States, Britain, and France

World War II: The Soviet Union

World War II: Germany and Italy

Small Arms and Machine Guns


Tanks and Armored Vehicles

Aircraft, Bombs, and Guidance Systems

Rockets, Missiles, and Nuclear Weapons

Chemical and Biological Weapons

Modern Fortifications

Sieges and Siege Techniques: Modern

Armies and Infantry: Modern

Cavalry: Modern

Naval Development: The Age of Propulsion

The Age of Bismarck

The “Great” War: World War I

The Spanish Civil War

Categories: History