The Battle of Nagashino (長篠の戦い Nagashino no Tatakai) took place in 1575 near Nagashino Castle (長篠城) on the plain of Shitaragahara (設楽原) in the Mikawa province (三河) of Japan. Forces under Takeda Katsuyori (武田勝頼) had besieged the castle since the 17 June; Okudaira Sadamasa (奥平貞昌), a Tokugawa vassal, commanded the defending force. The Takeda forces attacked the castle because it threatened Takeda's supply lines.