MED0022 – The Ii Naomasa’s Red Devils charge at Sekigahara

Ii Naomasa’s Red Devils at Sekigahara, 1600

On 21 October 1600, in a narrow valley wrapped in morning fog, two coalitions of Japanese lords met in the battle that decided who would rule the country for the next two and a half centuries. Sekigahara was not a war of conquest but a succession crisis: after the death of Toyotomi Hideyoshi, the regents appointed to govern for his infant heir split into two camps, the Eastern Army under Tokugawa Ieyasu and the Western Army under Ishida Mitsunari.

Armour built to be recognised

The unit at the centre of this painting is the Ii clan’s akazonae — the “red regiment” — whose entire harness, from helmet to shin guards, was lacquered vermilion. Japanese armour of this period was made of iron and leather plates laced together into flexible articulated sections, light enough for a mounted man to fight in and lacquered against the humidity that would otherwise destroy it. Colouring the whole unit served a practical purpose on a battlefield of dust and smoke: it made the formation instantly legible to friend and enemy alike, which was as much a psychological weapon as a command aid.

Firearms and the massed volley

By 1600 the Japanese battlefield had absorbed the arquebus for over half a century, and domestic production had surpassed European output in volume. Sekigahara was fought by armies in which massed matchlock infantry, drawn up behind field fortifications, mattered at least as much as the cavalry. The image of a purely sword-bearing samurai belongs to a later, peaceful era; the men who fought here served in combined formations of gunners, spearmen and horse.

A battle decided by defection

The engagement turned not on manoeuvre but on treachery. Kobayakawa Hideaki, holding a hill with fifteen thousand men and having negotiated with both sides, waited for hours before committing them against his nominal allies. Other Western commanders followed. Within a few hours a numerically balanced battle had become a rout, and Ishida Mitsunari was captured and executed.

What Sekigahara produced

Three years later Ieyasu took the title of shogun, founding a dynasty that governed Japan until 1868. Ii Naomasa, wounded by a bullet in the closing phase, received the domain of Hikone; his descendants held it for the whole Tokugawa period, and the red armour became one of the most recognisable emblems of the era.