Battle of Sekigahara

Battle Lines at Sekigahara the morning of October 21, 1600
Battle Lines at Sekigahara the morning of October 21, 1600

Gifu Sekigahara Battlefield Memorial Museum Image

In 1600, the village of Sekigahara was a small town along the Nakasendo road, a vital inland path connecting the east and west parts of the main Japanese island of Honshu from Edo (modern Tokyo) to Kyoto. Alongside the Tokaido, which followed a route closer to Honshu’s eastern shore, these two roads were the most important paths of transportation in the country at the time, and even today the shinkansen (bullet trains) pass over where these old roads once lay.

When Ishida Mitsunari withdrew his Western Army from Ogaki castle on the evening of October 20, 1600, he knew that his opponent Tokugawa Ieyasu's Eastern Army had little choice but to follow. Ieyasu’s objectives, the Ishida headquarters at Sawayama and the city of Osaka, lay at the end of the Nakasendo, and if he wanted to reach them, he had no choice but to confront the Western Army, which would be waiting for him near Sekigahara.

The Western Army’s approximately 80,000 men worked tirelessly in the darkness of that late, rainy night, taking up positions around the four hills overlooking the valley around the road through Sekigahara. Kobayakawa Hideaki, the 18-year-old veteran of the recent war in Korea, led about 15,600 men from his headquarters on Matsuoyama (Mount Matsuo) on the far-right flank of the Western Army. Several days before the battle, Hideaki had sent a message to Ieyasu saying that when the time came, he would join the Eastern Army in return for a reward of massive wealth and land. Hearing rumors of treachery, soon before the battle Mitsunari extracted a promise from the young general that he would remain loyal to the Western Army and would charge at the Tokugawa flank once Mitsunari lit a signal fire. By the dawn of October 21, neither side knew where Hideaki’s true loyalties lay, least of all Hideaki himself.
Modern day view from Mt.Sasao in Sekigahara, facing towards Mt. Matsuo on the right.
Modern day view from Mt.Sasao in Sekigahara, facing towards Mt. Matsuo on the right.

Gifu Sekigahara Battlefield Memorial Museum Image

To Hideaki’s left were the forces of Ukita Hideie, Otani Yoshitsugu, and Konishi Yukinaga, with some 21,000 men between them. Mitsunari himself was positioned at the far-left flank on the slopes of Sasaoyama (Mount Sasao), directly across from Hideaki and with 6,000 men directly under his command. A few miles to the east, about 28,000 men of the Mori clan stood waiting on Nanguyama (Mount Nangu), ostensibly ready to flank the attacking Tokugawa forces. Like Hideaki, however, the allegiance of Mori generals like Kikkawa Hiroie to Mitsunari loyalists was unclear.

By 4:30 a.m., the Western Army had essentially created a wall blocking Ieyasu from following the Nakasendo. With the two armies having essentially equal numbers – about 80,000 men each – the advantage in terrain seemed to belong to Mitsunari. But numbers and terrain are not the only consideration in such battles.

For his part, Ieyasu began to pursue Mitsunari at around 2:00 a.m. on October 21, setting up his command post on a small hill called Momokubari next to Nanguyama. His generals set up a line across the Nakasendo parallel to the Western forces in front of them. Ieyasu himself directly commanded about 30,000 men. Around 13,500 others took up positions on the road behind him just in case the Western Army’s Mori forces, whom Ieyasu had ostensibly convinced to join him, reneged on their promise.

About 20,000 men under Fukushima Masanori, Kuroda Nagamasa, Tanaka Yoshimasa, Hosokawa Tadaoki, Katou Yoshiaki, and Tsutsui Sadatsugu took up positions facing Mitsunari between Sasaoyama and the village of Sekigahara, with some 18,000 men behind them closer to the town.
Picture of a battle map of the western and eastern armies at 8 a.m.
Battle map of the western and eastern armies at 8:00 a.m.

Gifu Sekigahara Battlefield Memorial Museum Image

The battle of Sekigahara began about 7:30 a.m, October 21, 1600. After the intense rain of the previous night, the morning had been misty and none of the more than 150,000 soldiers in the area could see more than about one hundred feet in front of themselves. Once the fog cleared, though, it was the Eastern Army who struck first. Fukushima Masanori, whom Ieyasu had granted the honor of being the first to attack, began to advance towards the Western lines. Masanori had been a relatively late addition to the Eastern cause, however, and other generals under Ieyasu felt that the honor ought to go to someone with a longer history of loyalty. Thus, Ii Naomasa, deceitfully telling Masanori that he and his 30 men were simply on a scouting mission, charged into Ukita Hideie’s line of 17,000 men. Just as those horsemen retreated, the sound of thousands of gunshots went off as Masanori’s men opened fire on Hideie’s men and the battle began in earnest.
Picture of mountains near Sekigahara and a battle map of the western and eastern armies.
Battle map of the western and eastern armies at 10:00 a.m.

Gifu Sekigahara Battlefield Memorial Museum Image

There hadn’t been much time for either side to plan out a larger strategy for the battle, and so the first few hours proceeded in what historian Chris Glenn has called an "orderly free-for-all." The Eastern forces launched attacks on the Ukita lines and the forces on Sasaoyama, with action ranging from exchanges of gunfire to gruesome melee combat. By 10:00 a.m., in the words of one manuscript, “the smoke from the guns had blotted out the sunlight,” and the continued discharge of matchlocks was “louder than thunder.”

One typical example of the brutality of close-quarters combat during this period came early in the battle during this clash between the Ukita and Fukushima forces. Kani Saizo, one of Masanori’s officers, fought against his counterpart Akashi Takenori. Stabbing and slashing his naginata – a Japanese polearm – against Takenori’s attempts to block and parry, Saizo finally knocked him to the ground and cut the head off of his wounded opponent. It was a traditional custom during this period for warriors in combat to claim the heads of their slain foes. At the end of a battle, all the captured heads would be registered and presented to the army’s leader, with more merit and honor going towards those fighters who had claimed the heads of the highest rank. By the end of the battle, Saizo alone had seized 17 enemy heads.

Ninety minutes into the battle, Shima Sakon, who had advised Mitsunari against a night attack near Ogaki castle, became an early casualty for the Western forces, and a bad omen for the course of the battle. Caught in a volley from Eastern matchlocks, he received gunshot wounds to his chest and elbow and was knocked from his horse. His men quickly carried the wounded general off the battlefield, but his injury dealt a blow to Western morale. To rally his own side, Ieyasu moved his command post forward to just outside the village.

All this time, the Western forces to the east on and around Nanguyama – about 25,000 men – had been standing idle, even as the Eastern Asano Yukinaga began to attack their ally on the slopes, Natsuka Masaie. None of them dared to fight unless Kikkawa Hiroie, who had taken position in front, acted first. Eventually, Hiroie’s impatient allies sent him messages inquiring whether he intended to fight at all. Not once but three times throughout the battle, he replied that he was not yet ready: he and his men were in the middle of eating lunch.

Another important general who was conspicuously inactive during the early battle was Kobayakawa Hideaki on Matsuoyama. Even after Mitsunari fired signal flares into the sky and both Otani Yoshitsugu and Konishi Yukinaga sent messengers up Matsuoyama, the Kobayakawa forces made no sign of movement. Having sworn allegiance to both the Tokugawa and the Toyotomi loyalists, and, in turn, having been promised rewards from both, the young Hideaki seemed unable to make up his mind as to which side he was on.

On the Western left, next to Mitsunari’s position, Shimazu Yoshihiro and his 2,000 men were also immobile despite the many orders they received from their nominal commander to join the fray. Eventually, around 11:00 a.m. Mitsunari himself rode out to demand answers from Yoshihiro. Yoshihiro declared that "there have been too many unpleasant dealings between us, I won’t fight for the likes of you!”
Battle map of the western and eastern armies at 12:00 p.m.
Battle map of the western and eastern armies at 12:00 p.m.

Gifu Sekigahara Battlefield Memorial Museum Image

By 12:00 p.m., as the Eastern forces continued to advance west from the village, Ieyasu knew that he was essentially trapped in the valley. Just like Mitsunari, Ieyasu was growing anxious about Hideaki’s inaction. If the Kobayakawa on Matsuoyama assailed his flank or the Mori on Nanguyama attacked his rear, there were very few options available. Impatient of Hideaki’s idleness, and eager for a signal clearer than any flares, Ieyasu ordered a group of matchlockmen to move forward and fire on Hideaki's men on Matsuoyama.

Finally, Kobayakawa Hideaki made his decision, ordering his men to charge down Matsuoyama and attack Otani Yoshitsugu. Although the leprous Yoshitsugu had anticipated Hideaki’s treachery and effortlessly adjusted his lines to guard his flank, Hideaki’s 15,000 men horribly outnumbered Yoshitsugu’s 600, even without the Eastern forces attacking them in the front. Knowing hope was lost, Yoshitsugu committed seppuku and asked one of his retainers to hide his head so that the Eastern forces would not claim it as a trophy. He was apparently successful, as his head was never found.
Ghost of Otani Yoshitusugu haunting Kobayakawa Hideaki for his betrayal at Sekigahara
A woodblock print by Yoshitoshi depicting the vengeful ghost of Otani Yoshitsugu haunting Kobayakawa Hideaki for his betrayal at the Battle of Sekigahara.

Yoshitoshi's 'Selection of 100 Warriors'

The Western lines began to crack under the pressure of being attacked from two sides. Around 1:00 p.m., Ukita Hideie and Konishi Yukinaga fled from the battlefield, seeing no hope of victory at this point. As a Christian, Yukinaga was unable to kill himself, and soon after the battle he turned himself in to Ieyasu. Mitsunari himself fled around 1:30 p.m. Shimazu Yoshihiro and his nephew Toyohisa decided to retreat through the advancing Eastern army, and on their way out, dozens of samurai stayed behind to hold off their pursuers. One of their bullets even managed to wound Ii Naomasa in the arm, knocking him from his horse.

The 28,000 Western forces on Nanguyama, despite their strength, numbers, and ideal position in Ieyasu’s rear, had done virtually nothing the whole battle. Indeed, Kikkawa Hiroie had been a turncoat all along and had promised Ieyasu not to fight the Eastern army as an attempt to secure a more favorable position for the Mori clan in the new Tokugawa-dominated Japan. Seeing that the battle was over, the Mori also took their leave of the battlefield.

At 2:30 p.m., the victorious Tokugawa Ieyasu conducted the head-viewing ceremony. About 30,000 men lay dead, more than four times the number of deaths at the Battle of Gettysburg. Ieyasu had crushed the last, greatest threat to his power. In the years to come he would be declared shogun by the emperor and would annihilate the last vestiges of the Toyotomi loyalists, including Hideyori himself, at the Siege of Osaka in 1615.
Marker at the site of the Head Viewing Ceremony at Sekigahara.
Marker at the site of the Head Viewing Ceremony at Sekigahara.

Gifu Sekigahara Battlefield Memorial Museum Image

But for all intents and purposes, the Battle of Sekigahara marked the end of the long Sengoku period and the beginning of the Edo Period (so called because the new de facto capital was in the future Tokyo), marked by 260 years of isolationism, economic and cultural development, and above all peace and stability in sharp contrast to the previous century and a half. The Tokugawa Shogunate would last until the Meiji Restoration of 1868 put the imperial court back in control of Japan.

All of that was in the future, however, and Ieyasu knew always to expect the unexpected. Even as he overlooked the bloody field, finally triumphant, he sternly tightened the cords of his helmet as if prepared for more fighting. “Katte kabuto no o wo shime yo,” he said, in a phrase that would become a Japanese idiom. “Tighten the strings of your helmet after victory,” because, after all, you never know what could happen next.

The defeated Ishida Mitsunari delivered a similar sentiment soon after the battle, when he was captured and awaiting execution. Offered persimmons as a courtesy before his death, Mitsunari declined, insisting that they would be bad for his digestion. Konishi Yukinaga, who was to be beheaded as well, was incredulous, asking how Mitsunari could be so concerned about digestion when he was going to be dead in a few moments. “You never know what will happen,” Mitsunari replied.

Learn more about Sekigahara

Last updated: October 4, 2022

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