The first president of the United States to be impeached was Andrew Johnson. He was impeached by the House of Representatives on February 24, 1868, primarily for violating the Tenure of Office Act by attempting to remove Secretary of War Edwin Stanton without Senate approval

. Johnson's impeachment stemmed from his opposition to congressional Reconstruction policies following the Civil War. Although impeached, Johnson was acquitted by the Senate and remained in office until the end of his term in 1869