Benton served in the Senate as a Jacksonian Democrat for 30 years, although as a young man he fought Andrew Jackson in a duel. Benton also changed his mind about slavery. At first, he supported its expansion into Western territories. But later, he concluded that slavery hindered Western settlement and undermined national unity.
Thomas Hart Benton, daguerreotype by Mathew Brady, ca. 1844–1858
Prints and Photographs Division, Library of Congress