John A. McClernand was a leading Democratic congressman from Illinois who in 1861 became a brigadier general in the Union army. Although a “political general,” he proved himself on the battlefield until he ran afoul of Ulysses S. Grant and was relieved of his command of the Thirteenth Corps in 1863 during the Vicksburg campaign. Richard Kiper presents a balanced and sympathetic assessment of this highly controversial individual who served his country as soldier and statesman and sheds new light on the Union command system, providing insight into the politics of war as well as the personalities and relationships among the army’s senior officers.