Date Masamune came closest of any northeastern lord to building an independent power base that might have challenged the great unifiers. By the time he had dominated Oshu (northeastern Honshu), Toyotomi Hideyoshi had already largely settled Japan’s political future. Masamune spent the rest of his long life — he died in 1636, well into the Edo period — as one of the great Tokugawa-era lords, channelling his ambition into building Sendai and conducting extraordinary diplomatic ventures.

The One Eye

Masamune lost the sight in his right eye to smallpox, probably around age five. As an adult, accounts differ on whether the damaged eye was removed voluntarily (reportedly at Masamune’s own insistence, to prevent it from being a weakness an enemy could exploit) or through illness complications. The result was the most distinctive physical feature in Sengoku portraiture — a socket covered by a metal plate in formal portraits. [history] [legend: specific circumstances of eye removal vary by source]

He wore this disfigurement as identity rather than concealment. His helmet — a large black kabuto with a large golden crescent moon crest — was designed to be seen from a distance. The combination of the missing eye and the crescent moon crest made him immediately recognisable. [history]

Rise to Power

Masamune became head of the Date clan in 1584 at the age of seventeen, after his father Terumune voluntarily retired. He immediately began an aggressive expansion policy, attacking neighbouring clans and steadily consolidating control over the Oshu region. [history]

The defining moment was the Battle of Suriagehara (1589) against the Ashina clan of Aizu. Masamune won decisively, bringing most of Oshu under his control. At twenty-two, he controlled a domain larger than many daimyō twice his age. [history]

His methods were vigorous. Contemporary accounts describe hard campaigning and efficient administration. His nickname “Dokuganryu” (One-Eyed Dragon) reflected both his appearance and his reputation. [history]

The Meeting with Hideyoshi

By 1590, Masamune’s expansion had attracted Hideyoshi’s attention. As part of the final phase of unification — the Siege of Odawara campaign against the Hōjō — Hideyoshi summoned all daimyō to attend. Masamune arrived late, reportedly wearing white burial robes as a gesture of acceptance of whatever judgment Hideyoshi chose to impose — a dramatic statement of submission that acknowledged his late arrival might be treated as defiance. [history] [legend: the white robes story is from later accounts and may be embellished]

Hideyoshi accepted his submission but stripped him of the domains he had recently acquired — giving them to other lords. Masamune retained his core Date holdings but lost the fruits of his rapid expansion. He was twenty-three. [history]

The Early Edo Period and Sendai

Masamune supported Tokugawa Ieyasu at Sekigahara (1600), fighting on the eastern side, and was rewarded. He established his new domain capital at Sendai in 1601, building it from essentially nothing into a substantial castle town. Modern Sendai — a major city in Miyagi Prefecture — traces its urban origins directly to Masamune. [history]

In 1613 he dispatched an extraordinary diplomatic mission to Europe — the Keicho Mission — led by his retainer Hasekura Tsunenaga. The mission reached Rome via New Spain (Mexico), where Hasekura met Pope Paul V. The purpose is debated: possibly seeking trading relations, possibly related to Christian politics in Japan, possibly Masamune’s characteristic large-scale thinking. The mission returned in 1620 to find Japan’s Christian community being suppressed and its results were negligible. It remains the most distant diplomatic venture of any Sengoku-era daimyō. [history]

Legacy

Masamune lived until 1636 — long enough to see three Tokugawa shoguns and the stabilisation of the Edo order. He died in Edo at sixty-eight, interred at the elaborate mausoleum of Zuihoden in Sendai. [history]

He is by far the most celebrated historical figure in the Tohoku region — a constant presence in Japanese media, with statues, museums, and festivals in Sendai dedicated to his memory. His dramatic persona — the missing eye, the crescent moon helmet, the ambition that almost unified the north — translates powerfully into popular culture.