Japan: Medieval Summary

  • Last updated on November 11, 2022

Two outstanding political institutions dominate most of Japanese history until 1867: the samurai warrior class and the shogun military dictators.

Political Considerations

Two outstanding political institutions dominate most of Japanese history until 1867: the samurai warrior class and the Shogunsshogun military dictators. It is not exactly clear when the first Japanese state appeared, but Chinese and Korean chronicles speak of a recognizable kingdom at least by the fourth century c.e. In the fifth and six centuries, powerful families and clans residing in the area of present-day Kyoto and Osaka became united into the Yamato Yamato CourtCourt, the first real political entity in Japanese history. These hereditary clans, known as uji, controlled the majority of the population: the peasants, or be, who were grouped in caste-like fashion by occupation, residence, and family.Japan;medievalJapan;medieval

The uji-be Uji-be system (Japan)[Ujibe] system was modified in 645, but a characteristic feature of Japanese government at this time was the use of outpost soldiers, or sakimori, who guarded the borders. Sakimori (Japanese soldiers) Sakimori protected strategic locations, such as outlying islands in the south and mountain passes in the north. An incipient standing army, these frontier guards were also sent on expeditions of various kinds, such as fighting the indigenous Ainu Ainu people people in the northern territories. Although troops were initially provided by only the most powerful clans, by the eighth century each provincial governor was expected to provide a certain number (sometimes up to one-third of the male population aged sixteen to fifty-nine) of peasant-soldiers for three-year commitments. This policy was intended to break up the monopoly on military power held by the influential families.

However, the government, unable to control the activities of the remnants of the local uji clans in certain distant provinces, sent officials to these areas to oversee its interests and supervise the local administrations. The government also began granting land and tax exceptions to loyal subjects and to the younger sons and relatives of the court who, under the system of Primogeniture;Japanese primogeniture, would not inherit their family’s wealth.

A two-year smallpox epidemic beginning in 735 decimated the country, killing at least a quarter of the population and causing a severe labor shortage. As a result the government was economically unable to provide for a standing army, and landowners and aristocrats–as well as the officials previously sent by the government–began recruiting kinsmen to form bands of warriors to guard their own estates. Eventually, these blood ties lessened, but the permanent use of groups of such soldiers, called Samurai“samurai,” or “those who serve,” became a common way for landowners to protect and expand their holdings. The relationship between these noble warlords, eventually termed Daimyos (Japanese warlords)“daimyo,” or “great names,” and their vassals became one of intense loyalty. The samurai themselves grew into a class of military elite, with leaders drawn from descendants from the imperial family.

Although it was nominally a monarchy, medieval Japan actually was not ruled by the reigning emperor. Since the mid-700’s, true power had lain in the hands of the Shogunsshogun, a military dictator who theoretically protected the emperor from revolutionaries or barbarous indigenous border tribes. Although emperors inherited their titles, shoguns were ambitious leaders who rose to power on the basis of individual military skill and political guile. These shogun warrior governments ruled Japan until the mid-nineteenth century.

Under the shogunate system, power was divided between court and regent, allowing social or political instability as each disputed matters of jurisdiction. Because the shogun ostensibly governed on behalf of the emperor, his control was never absolute. Often disgruntled daimyo warlords would have their own ambitions and might rebel. Some samurai were never even vassals of the shogunate to begin with and were reluctant to obey its commands. Occasionally emperors themselves would try to assert direct authority and start revolutions of their own. Of course, too, there were many disputes over shogunal succession, both from within the ruling families and from outsiders.

Military Achievement

Much of Japanese history centers on the struggles of the various shogunates and the resulting countrywide conflicts. Civil war was rampant, brutal, and endemic.

The Sengoku, or Warring States, Warring States period (Japan)period was a particularly cruel time. Perpetual fighting went on for more than a century, from 1477 to 1601. By the 1580’s two generals, Oda Oda NobunagaOda NobunagaNobunaga (1534-1582) and Toyotomi Toyotomi HideyoshiToyotomi HideyoshiHideyoshi (1537-1598), had succeeded in unifying Japan after fighting numerous battles against various clans and eliminating the last Ashikaga shogun, Ashikaga YoshiakiAshikaga YoshiakiYoshiaki (1537-1597). After the assassination of Nobunaga by one of his own generals and the death of Hideyoshi, the country again fell into civil war. Tokugawa Tokugawa IeyasuTokugawa IeyasuIeyasu (1543-1616), Hideyoshi’s successor, defeated a coalition of generals and warlords at the Battle of Sekigahara, Battle of (1600)Sekigahara in 1600.

The Battle of Sekigahara is considered the most important Japanese battle in premodern times, ending the almost constant warfare that had preceded it and finally uniting the country. Ieyasu moved the Japanese capital to present-day Tokyo and established a reign of peace that lasted some 250 years. During this time of peace, the samurai evolved from warriors to government bureaucrats, administrators, scholars, and intellectuals. Though still an armed elite, the samurai warrior caste had, after a thousand years of struggle, finally been tamed in probably the greatest military achievement in Japanese history.

Weapons, Uniforms, and ArmorSwords

The Swords;Japanesemost famous Japanese weapon of this time is undoubtedly the Japanese sword, which had been made in the islands since the eighth century. More than two hundred schools of sword making could be found, each with its own distinctive style and characteristics. By the tenth century Japanese swords were considered the best in the world, a distinction that lasted until an 1868 imperial edict limiting their production.

Swords came in a number of sizes, weights, and lengths. During the Muromachi period of government (1338-1573), it became common for samurai to carry matching pairs of swords: a long katana Katana (Japanese sword) sword with a blade about 2 feet in length and a short Wakizashi (Japanese sword) wakizashi sword with a blade about 16 to 20 inches in length. Only samurai were allowed to wear swords, tucked into sashes around the waist, in noncombat situations.


Although Spears;Japaneseregular foot soldiers would often carry swords, usually of inferior quality, their primary weapon was the long spear. Spears of every possible length and weight could be found, but one popular type of spear was the Naginata (Japanese spear)naginata: a curved steel blade placed on a polished wood staff of about 5 or 6 feet in length. The naginata was particularly effective against mounted attacks. The straight Yari (spear) yari was the most common type of spear, with a double-edged hardened steel blade placed at the tip.

Bows and Arrows

Japan Bows and arrows;Japanesehas always been famous for the art of Archers and archery;Japanesearchery, and for centuries the bow and arrow was the primary military weapon. Mounted archery was a favorite sport of the early imperial court, and troops of mounted archers played an important role in repelling the thirteenth century MongolsMongol invasion led by Kublai Kublai KhanKublai Khan (Mongol king)Khan (1215-1294). Arrows were made of fine points of steel, and the layered bows were especially powerful. By the fifteenth and sixteenth centuries, units of foot soldiers would advance while firing their arrows in alternating rows. Although it was not especially accurate, this steady stream of arrows flying at the enemy often forced defenders to break ranks.


Although Armor;Japanesearmor was used in Japan as early as 400, it was not until the ninth century that the distinctively Japanese style of armor known as Yoroi (Japanese armor)yoroi first appeared. This style remained basically unchanged until the modernization of Japan in the mid-nineteenth century. Medieval Japanese armor was some of the most intricate and beautiful in the world. Squares of metal were laced together with leather straps, allowing for a great range of motion. This supple armor gave mounted archers and swordsmen the flexibility needed to ride and fight and also afforded foot soldiers solid protection against piercing lunges or deflected blows. Japanese iron helmets were works of art unto themselves, displaying everything from antler horns to flags to demon faces.


A collection of Japanese swords, which, from the tenth to the nineteenth century, were considered the best in the world.

(North Wind Picture Archives via AP Images)

Uniforms Uniforms;Japanesewere not standardized in Japan until the late sixteenth century. Each warlord or clan had its own distinctive crest or coat of arms. Individual samurai, too, were quite idiosyncratic in their choice of dress. By the mid-sixteenth century, battles had become colorful. Samurai wore small flags, or Sashimono (Japanese flags)sashimono, on the backs of their armor to indicate their affiliations, and the foot soldiers and conscripts of a particular daimyo began to wear similar kinds of dress.

Military Organization

Even as late as the Battle of Sekigahara in 1600 the Japanese system of military organization differed from the regimental models found in Europe. The main operational unit was the individual daimyo’s Armies;Japanesearmy. Forces were placed in the field according to family or warlord, and orders were given to each unit’s individual leader, often without close coordination with the other field units. This lack of organized communication often caused severe logistical problems.

A group of samurai warriors, a class that served as Japan’s military elite throughout the medieval period.

(North Wind Picture Archives via AP Images)

Unit specialization in the Japanese army was not particularly pronounced. Japanese armies generally consisted of foot soldiers and archers. JapaneseHorses and horse riding;Japanhorses tended to be small, making Japanese mounted attacks less effective than those of the European knights. Samurai often rode to battle but dismounted to fight; organized Cavalry;Japanesecavalry units, then, were not especially popular. Artillery;JapanArtillery units were also unusual. After Japanese daimyo learned that stone Castles;Japanesecastles were necessary to withstand cannon attacks, all wood castles quickly disappeared. Japanese gunsmiths never really designed Siege warfare;Japanesesiege guns to destroy castle walls. Thus, individual artillery units were also rare.

Doctrine, Strategy, and Tactics

The famous battles of the Gempei Wars Gempei Wars (1180-1185)(1180-1185) and the Japanese Civil Wars Japanese Civil Wars (1331-1392)(1331-1392) established the strategies and tactics of Japanese warfare that would last for more than two hundred years. Typical military formations employed samurai armed with swords or bows and arrows, peasant foot soldiers armed with Pikes;Japanesepikes, and the occasional mounted samurai cavalry charge. It has been said by some military historians that these battles, for the most part, were little more than mass confusion. Although elaborate and colorful formations were often staged before the battle, no strict patterns were followed in fighting. Struggles often degenerated into numerous one-on-one fights pitting individual soldiers against one another, each man simply trying to stay alive and attempting to decapitate the nearest foe.

This form of battle owed much to the samurai ethos of personal bravery and honor. For example, Daidoji Daidoji YuzanDaidoji YuzanYuzan (1639-1730), in his book Budo shoshinshu, translated as The Code of the Samurai, recommended that a true warrior “never neglects the offensive spirit” and that he should follow the proverb “When you leave your gate, act as though the enemy was in sight.” According to the way of the samurai, the public demonstration of one’s personal individual honor on the battlefield was more important than large-scale military or geographic objectives. In fact, some samurai even discouraged the study of military strategy altogether. In another famous treatise on the samurai way of life, the Hagakure, which translates literally as “in the shadows of leaves,” and is often known as The Way of the Samurai, Yamamoto Yamamoto TsunetomoYamamoto Tsunetomo Tsunetomo (1659-1719) argues that “Learning such things as military tactics is useless. If one does not strike out by simply closing his eyes and rushing into the enemy, even if it is only one step, he will be of no use.” Indeed, it could be argued from the perspective of a millennium’s distance that these individual private battles were as much the real reason for fighting as anything else.

Japanese warfare before 1570, then, was a highly unstructured affair; troops underwent little training and few drills. Samurai leaders, too, paid little attention to a campaign’s supposed military goals. In the mid-sixteenth century, however, all this changed. A century of protracted civil war had altered the political climate and power dynamics in Japan. The central government and the shogunate were now vastly weakened, and the daimyo sought to enlarge their individual domains by force of arms. War came to be defined as warlord against warlord, clan against clan. To maintain this constant state of siege and countersiege, larger armies were needed. As there were not enough samurai (never more than 5 or 10 percent of the population), more and more peasant troops had to be used. These Ashigaru (Japanese foot soldiers)ashigaru, or foot soldiers, made up increasing portions of each of the daimyo’s forces.

By the 1580’s Nobunaga had realized the need for major changes, and his initial successes were due at least in part to his new ways of military thinking. Previously, a general in command of a smaller army had been able personally to inspire his troops with his own charisma, persuasion, and bravery. Now, with 20,000- to 50,000-man armies often commonplace, a leader’s method of training, tactics, and command control were as important as his swordsmanship. Nobunaga, for example, realized the importance of uniforms and unit insignias for his troops, both to make identification during battle easier and to instill a sense of unit cohesion and identity.

Another major sixteenth century development was the introduction of Firearms;Japanesefirearms in 1543. The first Guns;Japaneseguns brought to the country were Portuguese harquebuses, matchlocks, and muskets. Japanese daimyo immediately ordered their swordsmiths to start making copies. Within a few decades Japanese gunsmiths, working with high-quality Japanese copper, were some of the best in the world. Firearms became relatively inexpensive to produce and reliable to use. As early as 1549 Nobunaga bought five hundred Matchlocks;Japanesematchlocks from a local daimyo and established the first musket brigade in a Japanese army. By the 1570’s more than a third of all daimyos’ armies had Muskets;Japanesemuskets, which became the most important weapon in the Japanese arsenal.

Tokugawa Ieyasu defeated a coalition of generals and warlords at the Battle of Sekigahara in 1600, unifying Japan.

(Library of Congress)

These new weapons forced major changes in tactics, as Nobunaga was quick to realize. Nobunaga pioneered the use of Harquebuses;Japaneseharquebus volley fire as a major offensive tool, and others followed suit. In response to the adoption of firearms, the Infantry;Japaneseinfantry was reformed into structured formations and echelons, including second-line units held back as reserves, a notion not used effectively by the Europeans until the early seventeenth century. In skirmishes spearmen were placed to the rear and flanks of the infantry to protect against infiltrators, and musketeers guarded the infantry and spearmen from cavalry charges.

After a series of power struggles throughout the late sixteenth century, Ieyasu defeated a coalition of generals and warlords at the Battle of Sekigahara in 1600 and established peace in the land. At this point he issued an unprecedented series of decrees that would eventually remove firearms from the country. Gun manufacturing first was restricted to one location and eventually was abolished altogether. The decision to eliminate firearms had several possible motivations. First, there was a generally negative feeling at this time toward all things Western, including guns. Second, according to samurai ethics, it was considered cowardly to kill someone from a great distance without meeting him face-to-face on the battlefield. Third, Swords;Japaneseswords and the art of their use held special symbolic and aesthetic meaning in the minds of the samurai, who apparently felt almost naked without them. Finally and most simply, the country did not seem to need firearms. After stabilization by the Tokugawa Tokugawa familyfamily, Japan effectively cut itself off from the rest of the world for the next two and one-half centuries. Ironically, it was American gunboats in the 1850’s that reopened the door.

Medieval Sources

There are many surviving documents, books, images, and artifacts from medieval Japanese times that tell a great deal about the lives of the samurai, daimyo, shoguns, and emperors. For example, illustrated training manuals of the era include guides to musket marksmanship, fencing, hand-to-hand combat, and even ninja assassination techniques. Also, the extensive writings of individual warriors tell much about their personal lives and philosophies. For instance, the loneliness of the sakimori frontier guards is reflected in the Man’yō-shū, an anthology of sakimori poems collected around 800 c.e. and translated into English as Collection of Ten Thousand Leaves in 1967 by H. H. Fonda. The famous Gorin no sho (c. 1643; The Book of Five Rings, 1974), written by master swordsman and artist Miyamoto Miyamoto MushashiMiyamoto Mushashi Mushashi (1584-1645), is still read for its timeless insights on the philosophy of martial arts. The intrigues of the court and the shoguns are documented in the genre of war tales writings, the most famous of which is the Heike monogatari (c. 1240; The Tale of Heike, 1988). This collection of traditional tales of the five-year Gempei Wars (1180-1185) is probably the best existing expression of the samurai code of Bushidō (Japanese warrior code) bushidō, the virtue of martial loyalty.Japan;medieval

Books and Articles
  • Farris, William Wayne. Heavenly Warriors: The Evolution of Japan’s Military, 500-1300. Cambridge, Mass.: Harvard University Press, 1992.
  • Friday, Karl F. “Oda Nobunaga.” In The Reader’s Companion to Military History, edited by Robert Cowley and Geoffrey Parker. Boston: Houghton Mifflin, 1996.
  • _______. Samurai, Warfare, and the State in Early Medieval Japan. New York: Routledge, 2004.
  • Kure, Mitsuo. Samurai: An Illustrated History. Boston: Tuttle, 2002.
  • Miller, David. Samurai Warriors. New York: St. Martin’s Press, 2000.
  • Ratti, Oscar, and Adele Westbrook. Secrets of the Samurai: The Martial Arts of Feudal Japan. Edison, N.J.: Castle Books, 1999.
  • Sugawara, Mokoto. The Ancient Samurai. Tokyo: The East Publications, 1986.
  • _______. Battles of the Samurai. London: Arms and Armour Press, 1992.
  • Turnbull, Stephen. The Samurai Invasion of Korea, 1592-98. Illustrated by Peter Dennis. Botley, Oxford, England: Osprey, 2008.
  • _______. Samurai Warlords: The Book of the Daimyo. London: Blandford Press, 1992.
  • _______. Strongholds of the Samurai: Japanese Castles, 250-1877. Botley, Oxford, England: Osprey, 2009.
  • _______. Warriors of Medieval Japan. Botley, Oxford, England: Osprey, 2005.
  • Varley, Paul. “Warfare in Japan, 1467-1600.” In War in the Early Modern World, edited by Jeremy Black. Boulder, Colo.: Westview Press, 1999.
  • Varley, Paul, with Ivan Morris and Nobuko Morris. Samurai. New York: Dell, 1970.
Films and Other Media
  • Samurai Japan. Documentary. Cromwell Productions, 1997.
  • The Seven Samurai. Feature film. Toho, 1954.
  • Shogun. Television miniseries. NBC, 1980.

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