Iwatate was mobilized as a soldier in 764 to suppress FUJIWARA no Nakamaro's Rebellion and performed a great feat of slaying FUJIWARA no Nakamaro (Oshikatsu EMI) there.
764年に一兵士として藤原仲麻呂の乱の鎮定に出動し、藤原仲麻呂（恵美押勝）を斬る功績を立てた。