Battle of Sekigahara

Ishida, in his home Sawayama Castle, met with Ōtani Yoshitsugu, Mashita Nagamori, and Ankokuji Ekei. Here, they forged their alliance, and invited Mōri Terumoto to be its head. They formed what came to be referred to as the Western Army. Mōri seized Osaka Castle for their base of operations, since most of Tokugawa's forces had vacated the area to attack Uesugi.[8]

The battle

Japanese arquebus (Tanegashima) of the Edo era.

Ishida wanted to reinforce Mōri at the impregnable Osaka Castle. This would let Ishida control the capital of Kyoto and challenge the Tokugawa. To this end, Ishida's forces headed for Gifu Castle in order to use it as a staging area to move on Kyoto, since it was controlled by his ally Oda Hidenobu.[4]

Back in Edo, Tokugawa Ieyasu received news of the situation in the Kansai region and decided to deploy his forces. Ieyasu himself commanded 30,000 men and his subordinates led another 40,000 men. This made up the bulk of what would later be called the Eastern Army.[9] He had some former Toyotomi daimyō engage with the Western Army, while he split his troops and marched west on the Tōkaidō towards Osaka.

Since the Tokugawa army departed from Edo, it could only take two roads, both of which converged on Gifu Castle. Ieyasu marched on Gifu while Ishida Mitsunari was delayed at Fushimi Castle. This fortress was a halfway point between Osaka and Kyoto and was controlled by the Tokugawa ally Torii Mototada.[10] Ishida could not risk leaving a force that could attack his rear, so he marched on it. It took him ten days to capture Fushimi, and in that time Gifu Castle had fallen. This forced Ishida Mitsunari to retreat southward in the rain.[4] The rain was relevant in that the bulk of both armies were equipped with matchlock rifles (tanegashima), which required dry gunpowder to fire.

Tired from a day's march and their gunpowder wet from the rain, Ishida and his forces stopped at Sekigahara. Ishida deployed his troops in a strong defensive position, flanked by two streams with high ground on the opposite banks. His right flank was reinforced by daimyō Kobayakawa Hideaki on Mount Matsuo.[11]

On October 20, 1600, Ieyasu learned that Ishida Mitsunari had deployed his troops at Sekigahara in a defensive position. They had been following the Western Army, and benefited from considerably better weather. At dawn of the next day, the Tokugawa advance guard stumbled into Ishida's army. Neither side saw each other due to the dense fog caused by the earlier rain. Both sides panicked and withdrew, but this resulted in both sides being aware of their adversary's presence.[11]

Ishida held his current defensive position and Ieyasu deployed his own forces. He sent his allies' forces in a line to the front, and held his own troops in reserve. Around 8:00 am, wind blew away the fog, and both sides noticed their respective adversary's positions. Last-minute orders were issued and the battle began.[12]

Initially, the Eastern Army had 75,000 men, while the Western Army numbered 120,000.[1] Ieyasu had also sneaked in a supply of arquebuses.[11] Knowing that the Tokugawa forces were heading towards Osaka, Ishida decided to abandon his positions and marched to Sekigahara. Even though the Western army had tremendous tactical advantages, Ieyasu had already been in contact with many of the daimyō in the Western Army for months, promising them land and leniency after the battle should they switch sides.[11]

The battle started when Fukushima Masanori, the leader of the Tokugawa advance guard, charged north from the Eastern Army's left flank along the Fuji River against the Western Army's right centre. The ground was still muddy from the previous day's rain, so the conflict there devolved into something more primal. Ieyasu then ordered attacks from his right and his centre against the Western Army’s left in order to support Fukushima's attack.[11]

This left the Western Army's centre unscathed, so Ishida ordered this unit under the command of Shimazu Yoshihiro to reinforce his right flank. Shimazu refused as daimyō of the day only listened to respected commanders, which Ishida was not.[11]

Fukushima's attack was slowly gaining ground, but this came at the cost of exposing their flank to attack from across the Fuji River by Ōtani Yoshitsugu, who took advantage of this opportunity. Just past Ōtani's forces were those of Kobayakawa Hideaki on Mount Matsuo.[11]

Kobayakawa was one of the daimyō who had been courted by Tokugawa. Even though he had agreed to defect to the Tokugawa side, in the actual battle he was hesitant and remained neutral. As the battle grew more intense, Ieyasu finally ordered his arquebuses to fire at Kobayakawa's position on Mount Matsuo to force a choice. At that point Kobayakawa joined the battle as a member of the Eastern Army. His forces charged Ōtani's position, which did not end well for Kobayakawa. Ōtani's forces had dry gunpowder, so they opened fire on the turncoats, making the charge of 16,000 men mostly ineffective.[12] However, he was already engaging forces under the command of Tōdō Takatora, Kyōgoku Takatsugu, and Oda Yūraku when Kobayakawa charged. At this point, the buffer Ōtani established was outnumbered. Seeing this, Western Army generals Wakisaka Yasuharu, Ogawa Suketada, Akaza Naoyasu, and Kutsuki Mototsuna switched sides, turning the tide of battle.[13]

○ = Main daimyōs who participated in Battle of Sekigahara

● = Daimyōs who defected

	Daimyō	Kokudaka (ten thousands)		Daimyō	Kokudaka (ten thousands)
Western Army	Mōri Terumoto	120.5	Eastern Army	Tokugawa Ieyasu ○	256.0
	Uesugi Kagekatsu	120.0		Maeda Toshinaga	84.0
	Satake Yoshinobu	54.0		Date Masamune	58.0
	Shimazu Yoshihiro○	73.0		Katō Kiyomasa	20.0
	Ukita Hideie○	57.0		Fukushima Masanori ○	24.0
	Ishida Mitsunari ○	19.4		Hosokawa Tadaoki ○	18.0
	Konishi Yukinaga ○	20.0		Asano Yoshinaga ○	16.0
	Mashita Nagamori	20.0		Ikeda Terumasa ○	15.2
	Ogawa Suketada ●	7.0		Kuroda Nagamasa ○	18.0
	Ōtani Yoshitsugu ○	5.0		Katō Yoshiaki ○	10.0
	Wakisaka Yasuharu ●	3.3		Tanaka Yoshimasa ○	10.0
	Ankokuji Ekei ○	6.0		Tōdō Takatora ○	11.0
	Kobayakawa Hideaki●	37.0		Mogami Yoshiaki	24.0
	Oda Hidenobu	13.5		Yamauchi Kazutoyo ○	5.9
	Chōsokabe Morichika ○	22.0		Hachisuka Yoshishige	17.7
	Kutsuki Mototsuna ●	1.0		Honda Tadakatsu ○	10.0
	Akaza Naoyasu ●	2.0		Terazawa Hirotaka ○	8.0
	Kikkawa Hiroie ●	14.2		Ikoma Kazumasa ○	15.0
	Natsuka Masaie ○	5.0		Ii Naomasa ○	12.0
	Mōri Hidemoto ○	20.0		Matsudaira Tadayoshi ○	10.0
	Toda Katsushige ○	1.0		Tsutsui Sadatsugu ○	20.0
	Sanada Masayuki	3.8		Kyōgoku Takatomo ○	10.0

Before the fateful confrontation in Sekigahara, Ishida Mitsunari claimed Osaka Castle and planned to take hostages from relatives loyal to Toyotomi. He hoped to use them to force his rival generals to join his cause. He sought to make noble women as political hostages, Hosokawa Gracia, Kushihashi Teru, and other women were targets of Mitsunari's plan.

When Mitsunari's soldiers threatened to take Hosokawa's home, Hosokawa Gracia was killed to protect her honor by a family soldier named Ogasawara Shōsai. He and the rest of the residents committed seppuku to avoid capture. As the last notable survivor of the Akechi clan, the clan that planned and killed Oda Nobunaga, Gracia's death impacted both armies. The incident did much damage to Ishida's reputation, which greatly reduced his chances of recruiting more allies, some of whom were also secretly Christians.

After Hideyoshi's death, Kodain-in (Hideyoshi's chief consort) left Osaka Castle and lived as a castle in Kyoto. Hideyoshi's second wife, Yodo-dono, inherited the political power of both figures, as Hideyori was too young to lead the Toyotomi clan. Yodo-dono was present in the maintenance of the Western army, although she did not play a very notable role during the campaign. Subsequently, Ieyasu began to receive hostages, nobles who were involved with the Mitsunari army, such as Maeda Matsu, whose son, Maeda Toshimasa, was involved in the Western army, while her other son, Maeda Toshinaga, was an ally of the Eastern army. After Ieyasu defeated Mitsunari in Sekigahara, Kodain-in received several women from the Western army at her home.

Legend has it that the rōnin Miyamoto Musashi was present at the battle among Ukita Hideie's army and escaped the defeat of Hideie's forces unharmed. Musashi would have been around 16 years of age at the time. There is no hard evidence to prove whether Musashi was present or not for the battle. According to one account, the Musashi yuko gamei, "Musashi's achievements stood out from the crowd, and were known by the soldiers in all camps."[24] Musashi is reticent on the matter, writing only that he had "participated in over six battles since my youth".[25]

The cannons from the Liefde, the trading ship that English sailor William Adams came to Japan on, were used by Tokugawa's forces at Sekigahara.[26] It is unlikely Adams himself was at the battle, although some fictional accounts have entertained the possibility.

Present day Sekigahara battlefield memorials

The site of the Battle of Sekigahara was designated a National Historic Site of Japan in 1931. The site encompasses the sites of the initial position of Tokugawa Ieyasu (徳川家康最初陣地), the final position of Tokugawa Ieyasu (徳川家康最後陣地), the position of Ishida Mitsunari (石田三成陣地), the Okayama beacon (岡山烽火場), the grave of Ōtani Yoshitsugu (大谷吉隆墓), the east kubizuka (東首塚), and the west kubizuka (西首塚)[27]

The Battle of Sekigahara has been depicted in a number of works of literature. Ryōtarō Shiba wrote a three volume historical novel called Sekigahara on it in the 1960s. James Clavell's 1975 novel, Shōgun, includes a fictionalized version of both the political struggle and the battle.[28]

The battle did not ever get a full movie featuring it until 2017, with previous inclusions generally only including a brief snippet in passing, such as the beginning of the 1954 movie Samurai I or the 1991 film Journey of Honor. This changed with the 2017 film Sekigahara, which covers the rivalry between Ishida Mitsunari and Tokugawa Ieyasu before leading to the battle itself in the final third of the film. The film is somewhat notable in being a revisionist reassessment, showing Tokugawa more as an antagonist while Mitsunari is a man of honor and the main protagonist.[29] The 2008 BBC Docudrama television series Heroes and Villains included an episode which featured the battle.[30] . The anime Sengoku Basara: Samurai Kings depicts the different alliances and armies from a more fantastic (and less realistic) viewpoint, with a conclusion that wasn't as bloody as in history.

In games, GMT Games produced the 2011 block wargame Sekigahara: Unification of Japan, which attempts to reflect the patchy loyalties of the armies involved by having randomized cards represent the loyalty of specific armies; players know which of their units are "reliable" but their opponents are not necessarily sure.[31] The 2017 video game Nioh includes a mission related to the battle and features heavily fictionalized versions of the events leading up to it.[32]

• Bryant, Anthony (1995). Sekigahara 1600: The Final Struggle For Power. Osprey Campaign Series. 40. Oxford: Osprey Publishing. ISBN 978-1-85532-395-7.CS1 maint: ref=harv (link)
• Davis, Paul (1999). "Sekigahara, 21 October 1600". 100 Decisive Battles: From Ancient Times to the Present. Oxford University Press. ISBN 978-0-19-514366-9.CS1 maint: ref=harv (link)
• Wilson, William Scott (2004). The Lone Samurai: The Life of Miyamoto Musashi. Tokyo: Kodansha International.CS1 maint: ref=harv (link)

Paul Davis used the following sources to compile the chapter "Sekigahara, 21 October 1600" in 100 Decisive Battles: From Ancient Times to the Present "Sekigahara, 21 October 1600."

• De Lange, William. Samurai Battles: The Long Road to Unification Groningen: Toyo Press, 2020
• Sadler, A.L. The Maker of Modern Japan: The Life of Tokugawa Ieyasu London: George Allen & Unwin, 1937
• Sansom, George. A History of Japan from 1334–1615 Stanford University Press, 1961
• Turnbull, Stephen. The Samurai: A Military History New York: Macmillan, 1977

• SengokuDaimyo.com The website of samurai author and historian Anthony J. Bryant. Bryant is the author of the above-mentioned Sekigahara 1600: The Final Struggle for Power.
• Several strategy war games based on the battle: Sekigahara: Unification of Japan