Battle of Azukizaka
1564 CE.
Shown on the map at 34.930°, 137.178°.
The Battle of Azukizaka (小豆坂の戦い, Azukizaka no tatakai) or Battle of Batō-ga-hara (馬頭原の戦い, Batō-ga-hara no tatakai) took place on 15 February 1564, when Matsudaira Motoyasu (later renamed Tokugawa Ieyasu), sought to destroy the growing threat of the Ikkō-ikki, a league of monks, samurai, and peasants who were strongly against samurai rule.
Text from the Wikipedia article Battle of Azukizaka (1564), licensed CC BY-SA 4.0.