In 1582, during the Tenshojingo War, Hojo's detached force consisting of 10,000 men planned to attack Ieyasu from the rear, however, Ieyasu's 2,000 men, containing Mototada, drove them back and killed 300 of the Hojo force (the Battle of Kurokoma), and Mototada was given Gunnai region in Kai Province by Ieyasu, and became the lord of Tanimura-jo Castle.
天正10年（1582年）、天正壬午の乱で家康の背後を襲おうとした北条勢の別働隊10,000を鳥居元忠ら2,000が撃退し北条勢約300を討ち取り（黒駒合戦）、その後甲斐国郡内地方を家康より与えられ、谷村城の城主となる。