Edwin M. Stanton was an American lawyer and politician who served as Secretary of War under the Lincoln Administration during most of the American Civil War. His effective management of the Union war effort helped lead to victory, earning him a reputation for being a capable but difficult administrator. After Lincoln's assassination, Stanton remained as Secretary of War under President Andrew Johnson, but their policy differences led to a major political conflict. His attempted removal by Johnson led directly to the president's impeachment by the House of Representatives.