Edwin Stanton established a substantial legal career before entering national government. He handled major litigation in Ohio, Pennsylvania, and Washington, including disputed California land cases. Appointed attorney general by James Buchanan in December 1860, he opposed concessions to secession during the administration's final months.

Abraham Lincoln made Stanton secretary of war in January 1862. He brought forceful management to a department struggling with the scale of the Civil War. His responsibilities included recruitment, supplies, transportation, military appointments, and relations with commanders. He used the telegraph to follow campaigns and direct officers.

Stanton's methods produced friction with generals and civilians, but Lincoln sustained him because of his administrative energy and commitment to Union victory. His department sustained large armies and supported recruitment of Black soldiers. The same wartime authority also involved censorship, military detention, and restrictions on civil liberties, making his tenure controversial.

After Lincoln's assassination, Stanton directed the immediate federal response and the pursuit of the conspirators. He stayed under Andrew Johnson but opposed his Reconstruction policy and supported congressional efforts to protect freedpeople and constrain the restored southern governments.

Johnson suspended Stanton in 1867, and the Senate subsequently refused to endorse the removal. A renewed attempt to dismiss him in February 1868 became central to Johnson's impeachment under the Tenure of Office Act. Stanton stayed in the department while the struggle continued, then resigned after the Senate failed to convict the president. In December 1869 Ulysses S. Grant nominated him to the Supreme Court, and the Senate confirmed the appointment. He died four days later, before taking office. His principal achievements remained the organization of the Union war effort and his defense of congressional Reconstruction.