Sekigahara, battle of (1600). This was fought between Tokugawa Ieyasu (the ‘Eastern Army’) and Ishida Mitsunari (the ‘Western Army’), and was one of the most decisive battles in Japanese history. Ishida had carried out a night march to Sekigahara. His plans were that the main body would hold the Tokugawa in the centre while others would attack them in the rear. Early in the morning of 21 October the Western Army was fully in position. In the centre were the divisions under Ukita Hideie and Konishi Yukinaga. To the left of them was Ishida Mitsunari himself. On the right wing, straddling the Nakasendō road, were various contingents including Kobayakawa Hideaki.
By daybreak the Eastern Army had advanced along the Nakasendō to meet them on as wide a front as the narrow valley would allow them. There was a thick fog which persisted until about 08.00, when the fighting started. The central divisions were the first to engage, the first shots of the battle probably being fired by Ukita's troops at those of Ii Naomasa of the Eastern Army. Ukita was successful in driving the Easterners back, but they rallied and the fight swayed one way and then the other. All the main divisions were now engaged, and Ishida thought the moment opportune to light the signal fire that would bring Kobayakawa down from Matsuoyama. But Kobayakawa turned traitor and assaulted the flank of Ōtani. Ieyasu then ordered a general attack along the line, and further contingents of the Western Army changed sides.
In the meantime Kobayakawa's men swept through the defeated Ōtani troops, round the rear of Ukita, and attacked Konishi from behind. The Western Army began to break up. Only the army of the Shimazu clan were left intact. Putting himself at the head of 80 survivors Shimazu Yoshihiro succeeded in cutting his way through the Eastern Army. Unfortunately this route took them south-west of Mount Nangu where Ishida's reserve troops were stationed. Some had already decided to join Ieyasu, others were wavering, unsure what to make of the noise they could hear and the garbled reports they were receiving. The battle was already lost, so the very contingents who might have been able to reverse Ishida's defeat turned and marched away from Sekigahara. Ieyasu's victory enabled him to become shogun, establishing the Tokugawa dynasty which lasted until 1868.
— Stephen Turnbull
