During the end of Edo period, Nagahiro acted with great tact between Sabaku-ha (supporters of the Shogun) and Sonno-ha (a group of activists who admired the Emperor), and on August 31, 1868, he was awarded an increase of 10,000 koku at the discretion of the new government and ranked among feudal lords, and founded the Tawaramoto Domain there.
幕末期においては佐幕派と尊王派の間を巧みに立ち回り、慶応4年（1868年）7月14日、新政府の計らいで1万石に加増されて諸侯に列し、ここに田原本藩を立藩した。