President Andrew Johnson was the 17th President of the United States, serving from 1865 to 1869. He became president after the assassination of Abraham Lincoln. Johnson, a Southern Democrat, had previously been the Vice President and was known for his lenient approach to Reconstruction following the Civil War. Johnson's presidency was marked by conflict with Congress, particularly over his policies regarding the reintegration of Southern states. He faced impeachment in 1868, primarily due to his violation of the Tenure of Office Act, but was acquitted by a single vote in the Senate. His presidency remains one of the most controversial in American history.