Sengoku period

Beginning of the Sengoku period

Historians do not agree on a single event that marks the beginning of the Sengoku period. The traditional starting date is the outbreak of the Ōnin War in 1467, because the conflict severely weakened the political order centered on the Ashikaga shogunate in Kyoto. Other interpretations begin with the Kyōtoku incident in 1454, which initiated decades of warfare in the Kantō region, or the Meiō incident in 1493, after which powerful military families repeatedly deposed, installed, and competed for control of Ashikaga shōguns.

The Kyōtoku incident began when Ashikaga Shigeuji, the Kantō kubō and principal Ashikaga authority in eastern Japan, ordered the killing of his deputy, Kantō kanrei Uesugi Noritada, in 1454. The murder divided the warrior families of the Kantō between Shigeuji and the Uesugi-led coalition supported by the Kyoto shogunate. Shigeuji withdrew to Koga, from which he and his successors became known as the Koga kubō, while the shogunate established a competing Ashikaga authority at Horigoe. Although a settlement was reached in 1482, the conflict left the Kantō politically divided and is therefore sometimes treated as the regional beginning of the Sengoku period.

The Ōnin War grew from several interconnected disputes rather than from the Ashikaga succession alone. Rival branches of the Hatakeyama and Shiba families contested their respective leaderships, while Hosokawa Katsumoto and Yamana Sōzen competed for influence within the shogunate. The uncertain succession of Shōgun Ashikaga Yoshimasa, involving his brother Ashikaga Yoshimi and infant son Ashikaga Yoshihisa, became entangled with these existing rivalries. By 1467, the competing groups had assembled large armies in Kyoto under coalitions conventionally known as the Eastern and Western armies.

Fighting destroyed large portions of Kyoto but produced no decisive victor. The alliances were not fixed: participants changed sides, pursued local disputes, and continued fighting after Katsumoto and Sōzen both died in 1473. Warfare also spread beyond the capital as leading families fought over provincial successions and control of estates. The conflict in Kyoto ended in 1477 when Ōuchi Masahiro and the remaining Western forces departed, but the disputes that had fueled it were not resolved.

The Ōnin War did not immediately eliminate either the Ashikaga shogunate or every established provincial government. It instead accelerated an uneven process of political decentralization. Some shugo returned to their provinces and strengthened their territorial authority, while others lost power to deputy governors known as shugodai, provincial warriors known as kokujin, or rival branches of their own families. Local communities and religious organizations also formed leagues called ikki, including the provincial league that governed southern Yamashiro Province after 1485 and the Ikkō-ikki that took control of Kaga Province in 1488.

The regional rulers later described as sengoku daimyō emerged gradually from several different backgrounds. Some descended from established shugo families, while others were former shugodai, kokujin or retainers who displaced their superiors. What distinguished them was not simply the absence of a shogunal appointment, but their ability to exercise comparatively direct military, judicial and fiscal authority over a defined territory. Even then, their power depended upon alliances with subordinate warriors, villages, temples and commercial communities.

Some recent scholarship, particularly in Japan, places the beginning of the Sengoku period at the 1493 Meiō incident. While Shōgun Ashikaga Yoshitane was campaigning against Hatakeyama Yoshitoyo, kanrei Hosokawa Masamoto seized Kyoto, removed Yoshitane, and installed Ashikaga Yoshizumi as shōgun. Yoshitane escaped and continued to claim the office, producing rival shogunal lines supported by competing military coalitions. From this interpretation, the Meiō incident was more decisive than the Ōnin War because it demonstrated that a leading retainer could depose a reigning shōgun and made control of the shogunate itself an object of prolonged military competition.

History

Start and end dates

Because the Sengoku period was a gradual breakdown and reconstruction of political authority rather than a formally proclaimed era, historians use different beginning and ending dates. The Kyōtoku incident of 1454 is sometimes used because it began prolonged warfare and divided Ashikaga authority in the Kantō region. The conventional date is 1467, when the Ōnin War began in Kyoto, while another interpretation favors the Meiō incident of 1493, when Hosokawa Masamoto deposed Shōgun Ashikaga Yoshitane and installed Ashikaga Yoshizumi.

An early ending date is 1568, when Oda Nobunaga entered Kyoto and installed Ashikaga Yoshiaki as shōgun. This date conventionally marks the beginning of the Azuchi–Momoyama period, but it did not end either the Ashikaga shogunate or warfare among the regional daimyō. The year 1573, when Nobunaga expelled Yoshiaki from Kyoto, is used when the end of the Sengoku period is equated with the termination of the Ashikaga shogunate and the Muromachi period. Nobunaga's move to Azuchi Castle in 1576 is another proposed transition point because it gave the later Azuchi–Momoyama period part of its name.

Another group of dates associates the period's end with the political unification of Japan. In 1587, Toyotomi Hideyoshi issued the sōbujirei, which prohibited daimyō from conducting private wars. His defeat of the Later Hōjō clan in the Odawara campaign of 1590 brought the last major independent regional power under his authority and is frequently treated as the completion of national unification. Hideyoshi's death in 1598 reopened the struggle for national supremacy, however, making 1590 an unsuitable endpoint for definitions that include the subsequent conflict between the Toyotomi and Tokugawa coalitions.

Later ending dates focus upon the establishment of Tokugawa rule. Tokugawa Ieyasu defeated his principal rivals at the Battle of Sekigahara in 1600 and was appointed shōgun in 1603, establishing the Tokugawa shogunate. The Toyotomi family nevertheless retained substantial autonomy at Osaka Castle until its destruction in the Siege of Osaka in 1615. Consequently, 1600 represents Tokugawa military supremacy, 1603 the institutional foundation of the new shogunate and 1615 the elimination of its last major rival.

The Sengoku and Azuchi–Momoyama periods therefore overlap under many systems of periodization. The latter generally describes the governments and unification campaigns of Nobunaga and Hideyoshi, beginning in 1568, 1573 or 1576 and ending with Hideyoshi's death, Sekigahara or the establishment of the Tokugawa shogunate. It should not always be understood as a wholly separate period beginning only after the Sengoku period had ended.

Hosokawa dominance of the Ashikaga shogunate

After the death of the ninth shōgun, Ashikaga Yoshihisa, in 1489, his cousin Ashikaga Yoshitane succeeded him as the tenth shōgun. Yoshitane supported Hatakeyama Masanaga in the continuing succession conflict within the Hatakeyama clan, but their policies brought them into opposition with kanrei Hosokawa Masamoto. While Yoshitane and Masanaga were campaigning against Hatakeyama Yoshitoyo in Kawachi Province in 1493, Masamoto seized control of Kyoto in the Meiō incident. Yoshitane was deposed and replaced by Ashikaga Yoshizumi, while Masanaga was defeated and killed. Yoshitane escaped captivity and continued to claim the shogunate, creating two rival Ashikaga lines supported by competing military coalitions.

As kanrei, Masamoto had been one of the shogunate's most senior officials, but his power after 1493 extended beyond the customary authority of that office. He controlled the government in Kyoto and exercised decisive influence over Yoshizumi's early administration. The kanrei is sometimes compared with the shikken of the earlier Kamakura shogunate, but the two offices developed in different political systems and were not direct equivalents. Masamoto's deposition of a reigning shōgun was a major break with established practice and is one reason that some historians use the Meiō incident as the beginning of the Sengoku period.

Masamoto had no biological children and adopted three prospective heirs from different families: Hosokawa Sumiyuki, originally a son of the aristocratic Kujō family; Hosokawa Sumimoto, from the Awa branch of the Hosokawa; and Hosokawa Takakuni, from another collateral branch. Masamoto initially favored Sumiyuki but later designated Sumimoto as his successor. In 1507, retainers supporting the disinherited Sumiyuki assassinated Masamoto in an event known as the Eishō no sakuran (永正の錯乱, Eishō disturbance). Sumiyuki did not personally kill Masamoto and did not retain power for long; supporters of Sumimoto and Takakuni defeated and killed him several weeks later.

The alliance between Sumimoto and Takakuni soon collapsed. In 1508, Takakuni joined former shōgun Yoshitane and Ōuchi Yoshioki, whose army advanced on Kyoto from western Japan. Yoshizumi and Sumimoto were driven from the capital, Yoshitane was restored as shōgun and Takakuni became the dominant Hosokawa leader in Kyoto. Fighting continued between the rival Yoshitane–Takakuni and Yoshizumi–Sumimoto coalitions, including the Battle of Funaokayama in 1511. After Yoshioki returned to his western provinces in 1518 and Sumimoto died in 1520, Takakuni exercised increased control over the shogunate. When Yoshitane broke with him in 1521, Takakuni installed Yoshizumi's son Ashikaga Yoshiharu as the twelfth shōgun.

Sumimoto's son Hosokawa Harumoto, supported by Miyoshi Motonaga, renewed the struggle against Takakuni. Their forces expelled Takakuni and Yoshiharu from Kyoto in 1527, although control of the capital continued to change hands. Takakuni subsequently allied with Uragami Muramune, but their coalition was defeated by Harumoto and Motonaga at the Battle of Daimotsu in 1531. Takakuni and Muramune were both killed, leaving Harumoto as the principal Hosokawa power in the central provinces.

Harumoto soon came to regard Motonaga's growing military influence as a threat. In 1532, he encouraged armed adherents of the Ikkō-shū to attack Motonaga, who was defeated and forced to kill himself at Sakai. The resulting Ikkō-ikki mobilization expanded beyond Harumoto's control and produced further warfare around Kyoto and Osaka. Although Harumoto temporarily dominated the shogunate, his dependence upon powerful retainers anticipated the subsequent rise of Motonaga's son, Miyoshi Nagayoshi.

Other regions

Chūgoku region (Mōri Motonari)

Mōri Motonari transformed the Mōri from a relatively small local warrior family in Aki Province into the dominant military power of western Honshu. The Mōri initially operated between the much larger Ōuchi clan, based in Suō and Nagato, and the Amago clan, based in Izumo. Motonari gained an early military reputation at the Battle of Arita-Nakaide in 1517 and became head of the Mōri clan in 1523 following the death of his young nephew. The battle was later compared with the Battle of Okehazama because Motonari defeated a larger Aki-Takeda force, but the description “Okehazama of the West” is a retrospective nickname rather than a contemporary name for the battle.

Motonari initially cooperated with the Amago but transferred his allegiance to the Ōuchi in 1525. During the following years he consolidated his position among the local warrior families of Aki. His survival depended partly upon Ōuchi support: when Amago Haruhisa invaded Aki and besieged Motonari at Yoshida-Kōriyama Castle in 1540, an Ōuchi relief army helped force the Amago withdrawal in January 1541. The victory substantially increased the Mōri clan's influence in Aki, but Motonari did not yet independently rule Aki, Iwami and Bingo as the previous version of this section stated.

Motonari strengthened his position through marriage, adoption and alliances as well as warfare. His eldest son, Mōri Takamoto, became heir to the main Mōri house, while his second and third sons were adopted into two important Aki families as Kikkawa Motoharu and Kobayakawa Takakage. The cooperation of the Mōri, Kikkawa and Kobayakawa houses gave the clan access to additional territory, soldiers and naval forces. The well-known “lesson of the three arrows”, in which Motonari supposedly demonstrated to his sons that three arrows bound together could not easily be broken, is a later legend. It reflects Motonari's documented insistence upon cooperation among his sons but is not known to have occurred as popularly described.

The political balance in western Japan changed in 1551 when Sue Harukata, a senior Ōuchi retainer, overthrew Ōuchi Yoshitaka in the Tainei-ji incident and installed Ōuchi Yoshinaga as the clan's nominal head. Motonari initially maintained relations with the new regime but broke with Sue in 1554. In the Battle of Itsukushima in 1555, Mōri forces defeated Sue's larger army and Sue killed himself. The defeat destroyed the military foundation of Yoshinaga's government. Mōri forces then advanced into the eastern Ōuchi territories, and Yoshinaga was forced to kill himself in 1557. The collapse did not transfer the entire Ōuchi realm to Motonari: the Mōri took its eastern territories, while the Ōtomo clan extended its influence over parts of the west and northern Kyushu.

After defeating Sue and the Ōuchi, Motonari concentrated on the Amago. Mōri forces gradually isolated the Amago stronghold of Gassantoda Castle, which surrendered in 1566 after an extended campaign. This established Mōri predominance across most of the Chūgoku region, although their authority remained contested by Amago restoration forces and by the Ōtomo in northern Kyushu. The Mōri consequently developed into a regional coalition rather than simply “pacifying” every province under uncontested personal rule.

Motonari formally transferred the clan leadership to Takamoto but continued to direct major political and military decisions. After Takamoto's death in 1563, Motonari supported his grandson Mōri Terumoto as heir while Motoharu and Takakage assumed leading military and administrative roles. Motonari died at Yoshida-Kōriyama Castle in 1571 at the age of 74. He left the Mōri as one of Japan's most powerful regional houses, controlling much of western Honshu and competing for influence in northern Kyushu.

Hokuriku, Kantō and Chūbu regions (Uesugi Kenshin)

The political order of eastern Japan had already been weakened by the conflicts between the Kantō kubō, the Uesugi clan and other regional families. In 1546, Hōjō Ujiyasu defeated a coalition led by Uesugi Norimasa and Uesugi Tomosada in the Battle of Kawagoe. Tomosada was killed and Norimasa was eventually driven from Kōzuke Province, allowing the Later Hōjō clan to become the leading power in much of the Kantō region.

Uesugi Kenshin was born Nagao Kagetora and belonged to the Nagao family, hereditary deputies of the Uesugi governors of Echigo Province. He replaced his elder brother Nagao Harukage as head of the Nagao in 1548 and gradually consolidated his authority among Echigo's frequently divided warrior families. Describing this process as the complete “unification” of Echigo in 1551 is misleading, because Kenshin continued to face resistance and negotiate with powerful local retainers throughout his rule. His government also depended upon control of commerce, ports, textile production and transportation networks rather than upon military conquest alone.

Uesugi Norimasa sought refuge with Kagetora after his defeat by the Later Hōjō and encouraged him to intervene in the Kantō. In 1559, Kagetora travelled to Kyoto, where he received an audience with Shōgun Ashikaga Yoshiteru and visited the imperial court. He launched a large Kantō campaign in 1560–1561, gaining the temporary submission of numerous regional lords and advancing to the Hōjō capital at Odawara Castle. Although his army burned parts of the castle town, it did not capture the fortress, and many of the alliances assembled during the campaign proved temporary.

In 1561, Norimasa adopted Kagetora into the Uesugi clan and transferred to him the Uesugi family name and claim to the office of Kantō kanrei. The succession was ceremonially recognized at Tsurugaoka Hachimangū in Kamakura. Kagetora subsequently used several names, including Uesugi Masatora and Terutora, before becoming best known by his Buddhist name, Kenshin. He continued campaigning in the Kantō during the 1560s, but the Later Hōjō recovered much of the territory that had temporarily submitted to him. Kenshin and Ujiyasu concluded an alliance in 1569 in response to their common conflict with Takeda Shingen, although the agreement did not permanently settle their territorial rivalry.

Kenshin's rivalry with Shingen developed from Takeda expansion into northern Shinano Province, where displaced local lords requested Kenshin's assistance. Their armies confronted one another during five campaigns around Kawanakajima in 1553, 1555, 1557, 1561 and 1564. These encounters are conventionally called the Battles of Kawanakajima, but most consisted principally of manoeuvring, sieges or limited skirmishing. Only the fourth campaign in 1561 produced a major pitched battle. It inflicted heavy casualties on both armies but did not result in a decisive or lasting territorial settlement.

During the 1570s, Kenshin increasingly concentrated upon the Hokuriku region. His forces expanded through Etchū Province and intervened in a succession conflict within the Noto Hatakeyama clan. After a prolonged campaign, Nanao Castle fell to the Uesugi in 1577, bringing most of Noto Province under Kenshin's authority. This expansion brought him into direct conflict with forces commanded by retainers of Oda Nobunaga. Later accounts describe the subsequent Battle of Tedorigawa as a major Uesugi victory, but the size of the armies, course of the fighting and extent of the Oda defeat are uncertain. It is therefore safer to state that the Oda army withdrew after confronting Uesugi forces than to claim that Kenshin decisively defeated Nobunaga personally.

Kenshin died suddenly at Kasugayama Castle in 1578 at the age of 48 under Western age reckoning, or 49 under the traditional Japanese system. His death is commonly attributed to a stroke or cerebral hemorrhage, but the surviving evidence does not establish a definitive medical diagnosis. Because he left no biological children and had not secured an uncontested successor, his adopted sons Uesugi Kagekatsu and Uesugi Kagetora fought for control of the clan in the Otate conflict, severely weakening the regional position Kenshin had constructed.

Firearms, warfare, and social change

According to the traditional account, Portuguese merchants introduced the European matchlock arquebus to Tanegashima in 1543. Earlier forms of gunpowder weaponry were already known in Japan, and some historians have suggested that matchlocks from other parts of Asia may have arrived before 1543. Nevertheless, the weapons acquired at Tanegashima provided the model for the Japanese firearm commonly called the tanegashima. Japanese craftsmen quickly reproduced the weapon, and manufacturing centers had developed at Negoro, Sakai and Kunitomo by the middle of the 1540s.

Matchlocks spread rapidly among the armies of the daimyō. They were commonly issued to organized groups of infantry and were used alongside bows and spears rather than immediately replacing them. Their effectiveness depended upon more than possession of the weapons: commanders also required trained gunners, gunsmiths, ammunition and reliable supplies of lead and saltpeter. Consequently, firearms increased the military importance of production centers, merchants and regional trade networks.

The adoption of firearms formed part of a broader expansion and reorganization of Sengoku armies, but it did not by itself create the ashigaru or cause the consolidation of Japan. Foot soldiers had played an important role before the introduction of the matchlock, and samurai as well as common soldiers used firearms. Larger armies and more centralized domains also depended on developments in taxation, castle construction, transportation, commerce and the administration of vassals. Firearms nevertheless favored lords capable of mobilizing substantial financial and logistical resources and contributed to the increasing size and complexity of late sixteenth-century warfare.

Oda Nobunaga became particularly associated with the organized battlefield use of firearms, most famously at the Battle of Nagashino in 1575. The allied Oda and Tokugawa army used matchlock troops and field fortifications against the attacking Takeda forces. Later accounts credited Nobunaga with deploying 3,000 gunners in rotating ranks, but the scale and tactical novelty of this arrangement are disputed. Recent scholarship concludes that Nobunaga probably possessed fewer firearms than later narratives claimed and that the evidence does not establish the celebrated system of continuous rotating volleys. Nagashino was therefore an important large-scale use of matchlocks in the field, rather than the first use of firearms in Japan or a single revolutionary event that transformed Japanese warfare.

Oda Nobunaga

Oda Nobunaga emerged as a major power after unifying most of Owari Province and defeating the substantially larger army of Imagawa Yoshimoto at the Battle of Okehazama in 1560. He subsequently conquered Mino Province, established his headquarters at Gifu Castle and adopted the seal Tenka Fubu, commonly interpreted as expressing his intention to bring the realm under military authority. His control of Owari and Mino provided the territorial and economic base from which he could intervene in the politically important Kinai region.

In 1568, Nobunaga marched to Kyoto in support of Ashikaga Yoshiaki, brother of the murdered shogun Ashikaga Yoshiteru. After overcoming the Rokkaku clan and driving the Miyoshi forces from the capital, Nobunaga secured Yoshiaki's installation as the fifteenth and final shogun of the Ashikaga shogunate. Although Yoshiaki provided Nobunaga with political legitimacy, their relationship deteriorated as Nobunaga restricted the shogun's independent authority. Yoshiaki eventually joined a coalition of Nobunaga's enemies. Nobunaga defeated him at Makishima Castle and expelled him from Kyoto in 1573, effectively ending the Ashikaga shogunate, although Yoshiaki continued to claim the title of shogun until 1588.

Nobunaga faced a series of overlapping conflicts rather than an uninterrupted succession of victories. His 1570 invasion of Echizen Province was abandoned after his brother-in-law Azai Nagamasa allied with Asakura Yoshikage and threatened the Oda army's route of retreat. Nobunaga and Tokugawa Ieyasu defeated the Azai–Asakura army at the Battle of Anegawa later that year, but the two clans continued resisting until 1573. Nobunaga then destroyed the Asakura stronghold at Ichijōdani and forced Yoshikage to commit suicide before capturing Odani Castle, where Nagamasa also died.

Resistance from Buddhist institutions and leagues of armed believers presented a longer challenge. Nobunaga conducted three campaigns against the Ikkō-ikki strongholds at Nagashima, finally destroying them in 1574. The war against Ishiyama Hongan-ji, led by Kennyo, lasted from 1570 until a negotiated evacuation of the fortress in 1580. The Hongan-ji received assistance from several of Nobunaga's enemies, particularly the Mōri clan, whose naval forces initially prevented the Oda from completely blockading the fortress.

In 1575, Nobunaga and Ieyasu defeated Takeda Katsuyori at the Battle of Nagashino. Matchlock troops and field fortifications contributed to the victory, although later accounts probably exaggerated both the number of firearms and Nobunaga's alleged use of continuous rotating volleys. Nobunaga later ordered campaigns conducted by his principal commanders: Shibata Katsuie expanded Oda authority in the Hokuriku region, Hashiba Hideyoshi advanced against the Mōri in western Honshu and Akechi Mitsuhide campaigned in Tamba Province. Nobunaga also constructed Azuchi Castle, which became the administrative and symbolic center of his expanding regime.

By 1582, Nobunaga directly governed central Japan and exercised authority over a wider coalition of subordinate lords, but he had not yet unified the entire country. The Mōri remained powerful in western Honshu, the Uesugi controlled territory in the north and the Chōsokabe, Shimazu and Later Hōjō remained independent. During the final campaign against the Takeda clan, Oda forces conquered Kai and Shinano and Katsuyori committed suicide. Later that year, while staying at Honnō-ji in Kyoto with only a small entourage, Nobunaga was attacked by Akechi Mitsuhide. He died during the Honnō-ji Incident on June 21, 1582. Hideyoshi subsequently defeated Mitsuhide and continued the process of unification begun under Nobunaga.

Toyotomi (Hashiba) Hideyoshi

Toyotomi Hideyoshi, then known as Hashiba Hideyoshi, rose from an obscure family in Owari Province to become one of Oda Nobunaga's principal commanders. Later accounts described him as the son of a peasant and an ordinary ashigaru, although the surviving evidence concerning his early life is limited and partly legendary. Under Nobunaga, Hideyoshi participated in campaigns in central Japan and was subsequently placed in command of the Oda advance against the Mōri clan in western Honshu.

When Nobunaga was killed by Akechi Mitsuhide in the Honnō-ji Incident in June 1582, Hideyoshi was besieging Bitchū Takamatsu Castle. He rapidly concluded a peace with the Mōri, concealed Nobunaga's death from them until negotiations were complete and marched his army eastward. He defeated Mitsuhide at the Battle of Yamazaki eleven days after Nobunaga's death. At the subsequent Kiyosu Conference, Hideyoshi supported Nobunaga's infant grandson Sambōshi as the formal Oda heir while distributing the former ruler's territories among the leading Oda retainers. This arrangement increased Hideyoshi's influence but did not immediately make him Nobunaga's undisputed successor.

Hideyoshi's principal rival within the former Oda regime was Shibata Katsuie, who supported Nobunaga's son Oda Nobutaka. Hideyoshi defeated their coalition at the Battle of Shizugatake in 1583, after which Katsuie and Nobutaka committed suicide. He began constructing Osaka Castle that year on the former site of Ishiyama Hongan-ji, making it the military and administrative center of his government. In 1584, Hideyoshi fought Tokugawa Ieyasu and Oda Nobukatsu in the Komaki–Nagakute campaign. Ieyasu won several tactical engagements, but neither side achieved a decisive overall victory. The conflict ended after Hideyoshi negotiated a separate peace with Nobukatsu; Ieyasu formally submitted to Hideyoshi only in 1586.

Hideyoshi extended his authority through a combination of military campaigns, negotiated submission and territorial redistribution. His forces compelled Chōsokabe Motochika to surrender most of Shikoku in 1585 and defeated the Shimazu clan during the Kyūshū campaign of 1587. In 1590, an enormous coalition of subordinate lords besieged the Later Hōjō clan at Odawara, while other Toyotomi forces captured its remaining fortresses. The Hōjō surrender was followed by the submission or confirmation of the major lords of the Tōhoku region. The suppression of the Kunohe rebellion in 1591 consolidated Toyotomi authority in northern Honshu. Although regional daimyō retained control of their domains, they were incorporated into a national political order centered on Hideyoshi.

Because his ancestry prevented him from becoming shogun, Hideyoshi obtained authority through the imperial court. He was adopted into the aristocratic Konoe family, appointed kampaku in 1585 and made Daijō-daijin in 1586, when the court granted him the family name Toyotomi. He relinquished the regency to his nephew Toyotomi Hidetsugu in 1591 and thereafter used the title Taikō, or retired regent, while continuing to exercise supreme authority.

Hideyoshi's government conducted nationwide cadastral surveys, standardized the measurement of agricultural production and redistributed domains according to assessed rice yields. His 1588 sword hunt ordered the confiscation of weapons from farmers and religious institutions. Together with restrictions on occupational mobility, these measures accelerated the separation of warriors from cultivators and strengthened the daimyō governments through which Hideyoshi ruled. He also promoted castle towns, commerce and control of strategically important mines and ports. These policies were not implemented uniformly or completed during his lifetime, but they influenced the administrative and social order later developed by the Tokugawa shogunate.

In 1592, Hideyoshi invaded Korea with the stated objective of advancing into Ming China. Japanese armies initially captured much of the peninsula, but Korean resistance, the naval campaigns of Yi Sun-sin, the intervention of Ming forces and difficulties supplying the occupying armies produced a military stalemate. After unsuccessful peace negotiations, Hideyoshi ordered a second invasion in 1597. Both campaigns caused extensive destruction and loss of life in Korea without securing Hideyoshi's objectives.

Hideyoshi's final years were dominated by the succession. Following the birth of his son Toyotomi Hideyori in 1593, Hideyoshi ordered Hidetsugu to commit suicide in 1595 and executed many members of Hidetsugu's household, eliminating the only adult Toyotomi successor. Before his death at Fushimi Castle on September 18, 1598, Hideyoshi established the Council of Five Elders and other governing bodies to protect the five-year-old Hideyori. Japanese forces withdrew from Korea after Hideyoshi's death, but the political settlement he created soon fractured, culminating in Tokugawa Ieyasu's victory at the Battle of Sekigahara in 1600.

Tokugawa Ieyasu

Tokugawa Ieyasu had been an ally of Oda Nobunaga and later became a subordinate, although sometimes reluctant, of Toyotomi Hideyoshi. After the Komaki and Nagakute campaign of 1584, Ieyasu eventually acknowledged Hideyoshi's supremacy and participated in the campaign against the Later Hōjō clan in 1590. Hideyoshi subsequently transferred Ieyasu from his ancestral territories in central Japan to the former Hōjō domains in the Kantō region. Although the transfer removed him from the politically important Kinai, it gave Ieyasu control of a large and economically productive territory. He established his headquarters at Edo, which later developed into the center of the Tokugawa government.

By the time of Hideyoshi's death in 1598, Ieyasu possessed the largest domain in Japan and was the most powerful member of the Council of Five Elders, which had been appointed to govern until the young Toyotomi Hideyori reached adulthood. Tensions developed between Ieyasu and other members of the Toyotomi government as he arranged political marriages and alliances without the required collective approval. His opponents accused him of attempting to appropriate Toyotomi authority, while Ieyasu presented his actions as necessary to preserve political order.

In 1600, the dispute divided many of Japan's daimyō into two coalitions. The Eastern Army supported Ieyasu, while the Western Army was organized principally by Ishida Mitsunari and nominally headed by Mōri Terumoto. The conflict culminated in the Battle of Sekigahara on October 21, 1600. The defection or nonparticipation of several Western commanders, most notably Kobayakawa Hideaki, contributed to Ieyasu's victory. Sekigahara did not immediately abolish the Toyotomi regime, but it left Ieyasu as the dominant military authority in Japan. He executed several leading opponents, confiscated or reduced the domains of defeated lords and redistributed much of their territory among his own allies and relatives.

In 1603, Emperor Go-Yōzei appointed Ieyasu shōgun, formally establishing the Tokugawa shogunate at Edo. Ieyasu transferred the title to his son Tokugawa Hidetada in 1605, demonstrating that the office would be inherited by the Tokugawa family, but he continued to exercise effective authority from Sunpu Castle. The emerging Tokugawa system preserved the regional domains of the daimyō while subordinating them to a hereditary military government. Lords were classified according to their relationship with the Tokugawa, strategically relocated and required to contribute labor and resources to major construction projects.

The Toyotomi family nevertheless retained Osaka Castle and considerable wealth and prestige under Hideyori. Relations between the two houses deteriorated as former Toyotomi retainers and other opponents of Tokugawa rule assembled at Osaka. During the winter and summer campaigns of the siege of Osaka in 1614–1615, Tokugawa forces captured the castle and destroyed the remaining Toyotomi leadership. Hideyori and his mother Yodo-dono died as the castle fell, and Hideyori's young son was subsequently executed. The fall of Osaka removed the last major rival to Tokugawa supremacy. Although historians use different dates for the end of the Sengoku period, the establishment of the shogunate in 1603 or the destruction of the Toyotomi in 1615 is commonly treated as the conclusion of the political and military unification that had begun under Nobunaga and Hideyoshi.

Events

Gekokujō

The weakening of the Ashikaga shogunate did not simply create an empty political vacuum. Authority became divided among shogunal officials, provincial military governors, their deputies, local warriors, temples, village communities and newly expanding territorial lords. During the resulting conflicts, individuals and organizations formally subordinate to an established authority could acquire enough military and political power to overrule or replace their superiors. This phenomenon was described as gekokujō, meaning approximately “the lower overcomes the higher”. It referred to the reversal of an accepted hierarchy rather than to a general system of social meritocracy.

Many cases of gekokujō occurred within the warrior elite. Provincial deputy governors, cadet branches and powerful retainers used family disputes, alliances and military victories to displace their nominal superiors. The Miyoshi, originally important retainers of the Hosokawa, became the dominant power in the Kinai under Miyoshi Nagayoshi. In Owari, branches of the Oda clan, which had served as deputies of the Shiba clan, gradually appropriated provincial authority. The Saitō clan similarly displaced the Toki governors of Mino. These changes were rarely straightforward transfers between two clans: rival branches, neighboring lords, temples and local warrior leagues often continued fighting for decades.

Hōjō Sōun, more accurately known during his lifetime as Ise Sōzui or Ise Shinkurō, was traditionally portrayed as a poor wandering warrior who rose entirely through his own ability. Later scholarship has established that he belonged to the Ise family, which served the Ashikaga shogunate, and possessed important connections to the Imagawa clan. He used those connections and the disruption caused by the Meiō incident to seize Izu Province and expand into Sagami Province. His son Hōjō Ujitsuna subsequently adopted the Hōjō name, and the dynasty now called the Later Hōjō remained a major Kantō power until its defeat by Toyotomi Hideyoshi in 1590.

Hideyoshi represented an unusually dramatic form of social advancement. His early life is poorly documented, but he came from an obscure family without the established military lineage of most leading daimyō. Through service under Oda Nobunaga, he advanced from a low-ranking retainer to a commander entrusted with major campaigns. After Nobunaga's death, Hideyoshi defeated his rivals among the former Oda leadership and eventually became kampaku and the paramount ruler of Japan. Nevertheless, the description of Hideyoshi as the nameless son of a peasant who rose through a formal series of ashigaru and samurai ranks derives partly from later biographical traditions and cannot be accepted in every detail.

Collective organizations could also overturn established provincial authority. The Yamashiro ikki expelled two competing Hatakeyama armies from southern Yamashiro in 1485 and administered the area through an association of local warriors and communities until 1493. In Kaga Province, followers of the Hongan-ji, allied local warriors and disaffected former retainers overthrew shugo Togashi Masachika in 1488. Political authority in Kaga subsequently remained divided among nominal Togashi governors, warrior families, local organizations and Hongan-ji institutions; it was therefore not simply an independent state governed by monks or peasants. Hongan-ji adherents became increasingly dominant during the sixteenth century and maintained substantial control until Oda forces conquered the province between 1575 and 1582.

The period's political mobility remained limited and did not abolish hereditary status. Successful Sengoku daimyō constructed new hierarchies, demanded greater obedience from their retainers and attempted to prevent the same kind of rebellion that had helped bring them to power. Hideyoshi's land surveys, sword hunt and restrictions on occupational movement further reduced the opportunities for armed cultivators and local warriors to challenge their superiors. Thus, gekokujō was both a feature of the fragmentation of medieval authority and a process eventually curtailed by the centralized regimes created during the unification of Japan.