Andrew Johnson (December 29, 1808 – July 31, 1875) was the 17th president of the United States from 1865 to 1869. Before becoming president, he was the 16th vice president of the United States from March to April 1865. He became president after Abraham Lincoln was assassinated. He was the first president to be impeached, but he was not removed from office. The impeachment happened because he fired the Secretary of War from his presidential cabinet after Congress had made it illegal. This was also considered strange, as it is usually up to the president to appoint and fire his secretaries. However, Congress hated him because he did not want to help slaves. Because of this, Johnson is widely regarded as one of the worst presidents in American history.