The Battle of Sekigahara

The Battle of Sekigahara, fought on October 21, 1600, was a pivotal conflict in Japanese history that marked the end of the Sengoku period and the beginning of the Tokugawa shogunate. This decisive battle between the forces of Tokugawa Ieyasu and Ishida Mitsunari resulted in Ieyasu’s victory, establishing his dominance over Japan and leading to over 250 years of Tokugawa rule. The battle is often considered the last major conflict before the unification of Japan and is remembered for its significant impact on Japanese politics and history.

Sekigahara—Samurai Showdown

Introduction

On the eve of a civil war in Japan, two friends spent a convivial evening together. They were Tokugawa Ieyasu, the most powerful lord in Japan, and Torii Mototada, the commander of one of Tokugawa’s castles. The next morning, the friends parted, knowing they would never meet again. Both understood that as soon as war broke out, their enemies would attack the castle; Mototada and the defenders would be outnumbered, yet as samurai, they would willingly stay and die for their lord. Soon after, 40,000 warriors besieged the castle, but Mototada held them off for 10 days, giving Tokugawa time to muster his own armies. Tokugawa went on to confront his enemies at the Battle of Sekigahara, the most decisive battle of the samurai era.

The Opponents

• (1) The Battle of Sekigahara would turn on the personalities of three people, all of whom had ties to Toyotomi Hideyoshi, the great warlord who had unified Japan and launched the invasions of Korea that had been repelled by Admiral Yi and his turtle ships.
• (2) The last of the unsuccessful Korean invasions had been dispatched in 1597 under the command of Toyotomi’s adopted son, a young samurai named Kobayakawa Hideaki. He was a figurehead as commander; much of the real decision making was done by a council of generals whose squabbling was a major factor in the failure of the expedition.
• (3) As the notional commander, Kobayakawa was summoned back to Japan in disgrace. Toyotomi apparently planned to punish him for his failure, but Tokugawa, who was already one of the most important lords in Japan, persuaded Toyotomi to be lenient.
• (4) Tokugawa was an experienced and wily general who had fought many battles and was a skilled tactician and strategist. He had helped Toyotomi gain control of Japan while biding his time and building up his own strength. He was in his mid-50s and at the apex of his wealth and power, with a network of allies who were loyal friends. Yet in his climb to prominence, he had made a number of enemies, and there were many who resented his prosperity.
• (5) In May 1598, near death, Toyotomi summoned the five most powerful lords, including Tokugawa, to act as a council of regents and rule the country in concert with five administrators until his old son was old enough to rule.
• (6) The leader of this group was Ishida Mitsunari, a descendant of a famous family that had fallen on hard times. It was these three men: Tokugawa, the powerful general and wealthy lord; Ishida, the clever administrator; and Kobayakawa, the young samurai, who would determine the outcome at Sekigahara.
• (7) Soon, two coalitions began to emerge: one centered on Tokugawa and his long-time friends and allies, and the other surrounding Ishida. In an official sense, Kobayakawa was clearly part of Ishida’s faction because Ishida was defending the legacy and wishes of Kobayakawa’s adoptive father, Toyotomi. This was also the group that supported the claim of Kobayakawa’s adoptive brother, Toyotomi’s 5-year-old son. On the other hand, Kobayakawa remembered the great favor that Tokugawa had done for him after the Korean debacle.

The Armies and Their Technology

• (1) The armies at Sekigahara fought with nearly identical weapons and armor.
  (a) The elite samurai were highly trained warriors proficient with a variety of weapons, including swords and bows. Some were mounted, although many fought on foot.
  (b) The ashigaru were lower-ranked and carried long stabbing spears called yari, while others were trained to fire primitive matchlocks.
• (2) Guns were a relatively new innovation, probably introduced by Portuguese traders in the mid-1500s, and the Japanese quickly learned to manufacture them. On the battlefield, the troops, thus armed, were deployed in mass blocks, where their volleys would have a shock effect.
• (3) Soldiers were equipped with a variety of body armor, ranging from solid breastplates to cuirasses formed of hundreds of metal plates held together with intricate bindings. This armor was frequently lacquered and, thus, could be brightly colored. Metal helmets were standard, as were shin and arm guards. Military units were not standardized; each lord organized his men as he wished.

The Battle

• (1) The actual battle was preceded by several months of hostilities, during which each side attempted to seize key castles occupied by the other. Ishida’s forces captured the castle of Fushimi, held by Tokugawa’s friend Mototada. Other Ishida-faction armies took Tanabe Castle and Otsu Castle, but these local victories obviously occupied some of Ishida’s forces, so they were not present at Sekigahara.
• (2) Meanwhile, Tokugawa’s generals seized the strategically located Gifu Castle, but Tokugawa’s son allowed himself to be delayed unnecessarily in attempting to take Ueda Castle. All these moves were like a chess game, in which the opposing sides sometimes expended strength to gain a strategic location or deliberately sacrificed a piece in one place to weaken an opponent’s attack in another.
• (3) Much of the maneuvering concerned control of two key roads: the coastal Tokaido road and the inland Nakasendo road. There is a point at which the main Japanese island of Honshu narrows, and both roads must squeeze through a slender gap between Lake Biwa and the Pacific Ocean. Near this natural chokepoint, where many of the contested castles were located, the two armies finally met on October 16, 1600.
• (4) Sekigahara lies in a constricted valley. Ishida’s forces converged here on the night of October 15 and were deployed on the hillsides and on bits of high ground, arrayed in a roughly semicircular shape. Ishida’s plan was to force Tokugawa’s army to cross the swampy lowlands and attack Uphil against his fortified positions, where they would be surrounded on three sides.
• (5) Ishida was stationed toward the left flank with about 8,000 men; from there, contingents under various lords stretched south in a curving line. Near the center was a block of 17,000 troops under the command of Ukita Hideie. On the far right flank, Kobayakawa was stationed at the head of 16,000 of his own men.
• (6) Across the valley, Tokugawa positioned himself on a hillside behind a double line of units totaling around 40,000. He held back his own 30,000 personal retainers in a block beside him as a reserve.
• (7) Both armies entered the valley during the night, but a thick mist obscured their movements so that neither was sure where the other was. As dawn broke, one of Tokugawa’s lords sprang forward at the head of 30 of his mounted samurai and launched a charge against Ukita’s center division. Following his lead, other Tokugawa units charged straight across the valley and engaged Ishida’s center and left divisions.
• (8) Ishida’s men were managing to resist the assault, but as he looked along the line, he noticed that one important contingent under Lord Shimazu was not participating. When messengers brought no explanation, Ishida went personally to see Shimazu and was brusquely informed that Shimazu would enter the battle when the time was right.
• (9) By late morning, most of Tokugawa’s forces, except for his reserve, had been drawn across the field and were heavily engaged. This was the moment that Ishida had been waiting for, and he gave the signal for Kobayakawa to descend from the hillside and engage Tokugawa’s army from the side. Kobayakawa did not respond. Even worse from Ishida’s perspective, several minor lords on the right flank of his army now emulated Kobayakawa and held back their troops as well.
• (10) Across the valley, Tokugawa was keeping an eye on Kobayakawa’s formation, well aware of the danger that Kobayakawa posed to the flank of his attacking forces. Like Ishida, he became focused on what the young lord would choose to do. Finally, Tokugawa was determined to force Kobayakawa’s decision; thus, he ordered a few of his musketeers to fire in the direction of Kobayakawa’s men.
• (11) The shots had an immediate effect. Kobayakawa sprang to his feet and exclaimed, “Our target is Otani!”—one of Ishida’s commanders. Kobayakawa’s men poured down the mountain and smashed into Otani’s regiment. Kobayakawa had chosen to switch sides and join Tokugawa.
• (12) This treachery did not come as a total surprise to Ishida and his men. They had been aware of Kobayakawa’s long vacillation, and Otani in particular had been so suspicious of his supposed ally that he had ordered a section of his men to be ready to turn and face Kobayakawa if he switched sides. Thus, Kobayakawa’s attack did not have the destructive impact it might have had against a wholly unprepared foe.
• (13) Otani’s men fought fiercely, but they were vastly outnumbered—a disadvantage that multiplied when the minor lords, who had also been delaying, now followed Kobayakawa’s lead, switched sides, and threw their lot in with Tokugawa.
• (14) At the other end of the line, Shimazu had finally joined the battle, but it was much too late, and the tide was now turning against Ishida. With Tokugawa’s forces pressing in from the front and Kobayakawa’s from the side, Ishida’s lines began to buckle, and individual commanders and units started to break away. By early afternoon, the victory would be Tokugawa’s.

Outcomes

(1) After Sekigahara, Tokugawa’s power was unrivaled. He redistributed land to reward his lords and punish his enemies. The still preadolescent son of Toyotomi Hideyoshi, in whose name Ishida had fought, was granted a large territory and allowed to live in Osaka Castle. In 1615, however, trumped-up charges were brought against him, the castle was besieged, and the last members of the Toyotomi clan were either killed or committed suicide.

(2) In 1603, Tokugawa took the title of shogun and effectively became the ruler of the United Japan. In 1605, he officially retired, although he continued to manipulate events behind the scenes. The dynasty that he founded, the Tokugawa shogunate, continued to rule Japan for approximately 250 years.

Conclusion

The Battle of Sekigahara stands as a decisive moment in Japanese history, marking the end of the tumultuous Sengoku period and the beginning of the Tokugawa shogunate’s long rule. Tokugawa Ieyasu’s victory not only solidified his power but also ushered in a period of relative peace and stability that lasted over two and a half centuries. This battle effectively reshaped the political landscape of Japan, laying the foundation for the country’s unification and the establishment of a centralized government. The legacy of Sekigahara is remembered as a turning point that defined the future trajectory of Japan, influencing its social, political, and cultural development for generations.

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