At the outbreak of the war, Polk was appointed as a major general in the Provisional Army of the Confederacy. He commanded the territory which included the Mississippi River defenses. Soon after, he was promoted to lieutenant general in October 1862. He served as a corps commander at the battles of Shiloh, Perryville, Murfreesboro, and Chickamauga. However, in the opening of the Atlanta campaign, he was killed by a cannon shot near Marietta, Georgia, in June 1864.
