Battles for Iwami Ginzan
The discovery of the Iwami Ginzan silver mine in 1527 occurred during a time of great unrest in Japan. This Sengoku (“warring states”) period was an epoch of constantly shifting alliances and rivalries among local warlord families. The Ouchi family, based in the southern province of Suo (present-day Yamaguchi Prefecture), was the first to assume control of the mine. Immediately after doing so, the Ouchi built a series of castles and other fortifications throughout the area to protect their mountain of riches from rival forces. These strongholds numbered more than a dozen and included Yamabuki Castle, the mine’s main fortress, the twin forts Yataki and Yahazu that guarded the road between the mine and the port of Yunotsu, and Iwami Castle, which overlooked the passage northwest to the coastal town of Nima. These outposts were the scene of many fierce battles throughout the 1530s and 1540s, when the Ouchi repelled repeated invasions by the local Ogasawara and Amago families.
The Ouchi’s hold on Iwami Ginzan began to unravel in the 1550s, when the powerful Mohri family of Aki Province (present-day Hiroshima Prefecture) extended its influence northward. Forces led by the warlord Mohri Motonari (1497–1571) assumed complete control over the area in 1562 and went on to fortify it further, establishing a naval base outside the port of Okidomari to protect both the silver shipments from that port and the supply route to nearby Yunotsu. The Mohri controlled the silver mine for almost four decades, until they and their allies were defeated by the Tokugawa clan in the decisive Battle of Sekigahara in 1600. Subsequently, the Mohri were confined to the province of Choshu at the western end of Honshu, and the Tokugawa took over Iwami Ginzan, bringing the battles for the silver mine to an end. Led by the warlord Tokugawa Ieyasu (1543–1616), they went on to unify the entire country under their banner, and in 1603 established the Tokugawa shogunate that was to rule Japan until 1867.