It has been known that Tadaharu distinguished himself in the Siege of Osaka and that he silenced a gun bugyo (military commissioner) of the Tokugawa family, who had accused him of an act in violation of the military command, by his overwhelmingly high competence.
大坂の役では武功を立てたほか、軍令違反を咎めた徳川家の軍奉行を器量で圧倒して黙らせるというエピソードを残している。