SUMMARY Nathaniel Prentiss Banks was a Massachusetts state legislator (1849–1853), a ten-term United States Congressman (1853–1857, 1865–1873, 1875–1879, 1889–1891), Speaker of the U.S. House of Representatives (1856–1857), governor of Massachusetts (1858–1861), and a Union general during the American Civil War (1861–1865). One of the most prominent political generals of the conflict, Banks lacked military talent and experience but rose to high command on the strength of his public stature and his staunch support of the administration of U.S. president Abraham Lincoln, despite having been one of Lincoln’s political rivals in 1860. Banks’s tendency to subordinate military affairs to political ambition, his penchant for grandiose planning without devoting sufficient attention to tactical details, and his inability to admit or correct mistakes ensured that a once-promising career in arms would fall short of expectations. As commander of the Department of the Shenandoah, he was outmaneuvered by Confederate general Thomas J. “Stonewall” Jackson in 1862, especially on May 25 at the Battle of Winchester. Jackson defeated him again at the Battle of Cedar Mountain on August 9, after which Banks was transferred to New Orleans, Louisiana. In the spring of 1864, he participated in the botched Red River Campaign in Texas, ending his field command. Banks returned to Congress after the war and died in Massachusetts in 1894.