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21st October 1600

Britain has the Battle of Trafalgar. America has the American Civil War. Japan has Sekigahara.

The battle of Sekigahara is Japan’s most notorious, and it was certainly one of the largest (if not the largest) in its recorded history. It was the culmination of the civil war between Tokugawa Ieyasu, daimyo of the Kanto plain and his rival Ishida Mitsunari.

The Background

Mitsunari had hoped to catch his adversary in a pincer movement, between his Western Army and the forces of Uesugi Kagekatsu. While Ieyasu moved to counter the latter, his army could move up to threaten Ieyasu’s base at Edo. However Ieyasu moved against Ishida, taking Ogaki Castle and allowing him to move rapidly West along the Nakasendo road. In order to stop the Eastern Army’s advance, Mitsunari had to give battle to his foe.

The Armies

On the day of the battle, the two opposing armies were fairly balanced in terms of size - around 85,000 each. Both the Western and Eastern armies were larger as a whole, but sections of them had been delayed by fighting elsewhere. For Ieyasu, his son Tokugawa Hidetada’s army was slowed down by laying siege to the Sanada clan in Ueda. On Mitsunari’s side, divisions were tied up in the siege of Otsu and Tanabe castles. There was little difference in terms of fighting ability or equipment. By this time, both sides were using muskets, originally imported by the Dutch and later copied in Japan. Bows were still in use but considered somewhat quaint by many samurai.

The Plan

Mitsunari and part of his forces took up positions on the Nakasendo near the village of Sekigahara. The rest were deployed on the high ground ready to trap Ieyasu. Kobayakawa Hideaki stood above Ishida's right side, forming a V-shape, ready to crash into the Eastern flank. Further to the east, Kikkawa Hiroie commanded the Mori and a taskforce to come from the rear. This was the old Chinese tactic - the "Crane's Wings". It was an excellent plan but did not account for treachery.

The Turncoats

Though the armies may have been mostly equal in terms of size, they were not equal in terms of unity. The Western army was mostly bound together to fight for Toyotomi Hideyoshi's son, not for their loyalty to Mitsunari. On the other hand, Ieyasu's forces were loyal to him himself, actually defying the "law" as it were. Though it was a pretext to further his own aims, Mitsunari was technically fighting for the legal heir.

Perhaps the most crucial turncoat was also the youngest. Kobayakawa Hideaki was only 17 at Sekigahara but the cause of his defection lay even earlier. At the age of 15 he had been appointed commander of the army in Korea in 1597. When the generals quarrelled and subsequently caused the collapse of the campaign, Mitsunari had blamed Hideaki. Ieyasu, however, had defended him. Hideaki remembered this. Also, his mother suggested siding with Ieyasu, when he went to her for advice.

Kikkawa Hiroie had been more loyal to the Western cause. However as the result of a slight by Ishida to the Mori, forcing their clan leader Mori Terumoto to stay out of the fight, he sent a secret message to Ieyasu. The Mori would not fight for him but neither would they engage the Eastern army.

The Battle

On the morning of the 21st, fog lay heavily across the battlefield, such that when it burned off, the lead elements of each side found themselves no more than a quarter of a mile apart. Who gave the order to attack is unclear but sometime after 8am, 30 horsemen from the Eastern army moved to attack. These were the "Red Devils" of Ii Naomasa, so-called because they were clad head to foot in red. Even their lances were lacquered red. They fell against Ukita Hideie, causing another section of the line to attack in competition. Though the honour of leading the charge was rightfully Lord Fukushima's, his samurai were forced to join in the attack.

Other daimyo joined in the assault. 20,000 men alone moved against Mitsunari's position. The fighting was horrendous as the attackers tried to break through the rings of defences around the command position. Battle was joined across most of the line across the Nakasendo. However Hideaki, the Mori and Shimazu had not yet joined in the fighting.

Despite desperate signals and messages from Mitsunari, the forces did not engage. Kikkawa Hiroie of the Mori had decided to betray him, and Hideaki was undecided. However old Shimazu Yoshihiro merely decided not to come to Mitsunari's aid. Later on in the battle his forces were engaged by the Eastern army - he was no traitor. The reason for this inaction was due to a slight the night before. He had suggested a night attack but had been shouted down by Mitsunari's strategist, Shima Sakon, who called it cowardice. Mitsunari had not defended him, so he would not now.

The crunch came when Hideaki joined the fray, sometime after 12pm. Ieyasu was determined to force him into the battle, so he ordered his musketeers to fire on the position just behind him. It spurred him into action and he fell upon Otani Yoshitsugu of the Western army. Yoshitsugu had placed divisions to deal with a flank attack, however these were engaged at the time. The buffer began to crumple and more Western commanders joined in the attack on their allies. Seeing the futility of the situation, Yoshitsugu, nearly blind and badly disabled, ordered a retainer to cut his head off. Yuasa Goro did as his master commanded and then hid the head, to stop it being taken as a trophy. Then he committed seppuku.

The turncoats now fell upon Ukita Hideaki and the other Western positions. They had not prepared for treachery and were already hard-pressed. Confusion and fear raged amongst the Western ranks - the front started to crumble. Mitsunari, many of his best commanders slain, withdrew. The Western army began to retreat en-masse. The day was Ieyasu's.

The Aftermath

Mitsunari was eventually captured and executed. Ieyasu could now take Osaka Castle and remove the only possible threat to his control - Hideyoshi's son Hideyori. However many of the daimyo who had fought with Ieyasu were endebted to Hideyori's father. So Hideyori was allowed to remain in Osaka with the provinces of Izumi, Kawachi and Settsu. In 1603 Ieyasu promised his 6 year-old grand-daughter as Hideyori's wife. It wasn't until 1615 that Ieyasu finally laid siege to Osaka Castle, on the pretext of being insulted at the poor wording of a prayer bell cast by Hideyori. Many of the Western daimyo joined Ieyasu. Hideyori committed seppuku and his clan were destroyed.

The battle played a great part in determining the future pecking order of daimyo and samurai during the Tokugawa Shogunate. Loyal retainers were given prime lands, whereas those who had opposed him were sometimes moved to remote areas, or fiefs with little income. After Sekigahara Ieyasu confiscated lands from 90 families - some 6.5 million koku, an incredible sum of money. Much of it filled Tokugawa coffers but many daimyo were rewarded for their help in the final battle. Hideaki received lands worth 520,000 koku, though he died only two years later and the lands returned to Ieyasu.

But it was in 1603 that Ieyasu received the greatest prize possible. Emperor Go-Yozei granted him the title of Shogun and official dominion over Japan. The Tokugawa Shogunate ruled Japan for another two and a half centuries.


At first Mitsunari looked to have been very unlucky to lose the battle. He had the superior plan and his enemy had no choice but to face him. However we must look at the events surrounding the battle to understand the reason for his demise.

Mitsunari was cunning at politics but in one way, he was too clever, too devious. He made too many enemies or insulted too many allies - for example the Shimazu and Mori were loyal until they were slighted. The Western army as a whole was united only by a vague sense of duty to Hideyoshi's heir. On the other hand, the Eastern army was united behind Ieyasu. He was supposedly prone to bursts of anger, yet he was still diplomatic enough to keep his men loyal.

As a result, Mitsunari's forces were far more open to betrayal than Ieyasu's. Ieyasu may have been banking too much on the planned defections, yet he was perceptive enough to know how sincere the turncoats were. Had he been unsure of their loyalty, doubtless he would have been more careful in the execution of his attack. As it was, he had been making his battle plans long in advance of the battle. Mitsunari ultimately failed because he was too short-sighted.


Anthony Bryant, Sekigahara 1600

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