Edwin McMasters Stanton was an American lawyer and politician who served as U.S. secretary of war under the Lincoln Administration during most of the American Civil War. Stanton's management helped organize the massive military resources of the North and guide the Union to victory. However, he was criticized by many Union generals, who perceived Stanton as overcautious and a micromanager. He also organized the manhunt for Abraham Lincoln's assassin, John Wilkes Booth.