Date Harumune

Date Harumune (1519-1578) was a Sengoku-period daimyo of Mutsu Province. The eldest son of Date Tanemune, the 14th head of the Date clan, he prevailed over his father in the Tenbun War to become the 15th head of the clan, and was the grandfather of Date Masamune.

Origins and Conflict with His Father

Harumune's mother was Taishin-in, a daughter of Ashina Moritaka. In 1542, when Tanemune attempted to send one of his sons (Harumune's younger brother) as an adopted heir to Uesugi Sadazane, the Echigo shugo, Harumune strongly objected and, in league with senior retainers, had his father confined at Nishiyama Castle.

The Tenbun War

Once Tanemune was rescued, a large-scale civil war — the Tenbun War — broke out, drawing in daimyo across southern Ōshū. Tanemune's side initially held the advantage, but the tide turned in 1547 when Ashina Morishi switched allegiance to Harumune. The conflict, which engulfed southern Ōshū for six years, ended in 1548 with a truce brokered under orders from the 13th Ashikaga shogun, Yoshiteru, confirming Harumune as the 15th head of the Date clan.

Relocation to Yonezawa and Reform of the Vassal Band

After securing the headship, Harumune moved his base from Kuwaori Nishiyama Castle to Yonezawa Castle. In 1553 he compiled the "Harumune-kō Saichi Kashiroku," a register that untangled the confirmations of land tenure issued haphazardly during the war and fixed the holdings and rank of his retainers. In 1555 the Ashikaga shogunate appointed him Ōshū Tandai, formally confirming his standing as a major power in southern Ōshū.

Children and Succession

With his principal wife Kubo-hime, daughter of Iwaki Shigetaka, Harumune had six sons and five daughters. His second son, Terumune, succeeded him as clan head; Terumune's son was Date Masamune, making Harumune the grandfather of Masamune.

Legacy

Edo-period Date family chronicles, mindful of his having confined his own father, often portrayed Harumune unfavorably as an "unwise lord." More recent scholarship, however, has reassessed his reorganization of the vassal band after the Tenbun War and his relocation to Yonezawa as a pivotal foundation that his grandson Masamune would later build upon.