Andrew Johnson (December 29, 1808 – July 31, 1875) was the 17th President of the United States (1865-9), succeeding to the Presidency upon the assassination of Abraham Lincoln. He is one of only two U.S. Presidents to be impeached, the other one being Bill Clinton. He is also the only former President to serve as a Senator after his presidency, which he did from March 1875 until his death later that year.
Johnson served as a United States Senator from Tennessee at the beginning of the American Civil War. He was the only Southern Senator not to quit his post upon secession, and became the most prominent War Democrat from the South. In 1862 President Lincoln appointed Johnson military governor of Tennessee, where he proved energetic and effective in fighting the rebellion. Johnson was nominated for the Vice President slot in 1864 on the National Union Party ticket, displacing incumbent Vice President Hannibal Hamlin, with Lincoln running for re-election.