Complex sentence: Entering politics as a Democrat and supporter of Martin Van Buren, he was appointed postmaster of Groton in 1841 and served in the Massachusetts House of Representatives from 1842 to 1844 and from 1847 to 1850.
Split into simpler sentences: Entering politics as a Democrat and supporter of Martin Van Buren, he was appointed postmaster of Groton. In 1841, Boutwell served in the Massachusetts House of Representatives from 1842 to 1844 and from 1847 to 1850.