Little is now known to the general public of the history of the attempt to remove President Andrew Johnson in 1868, on his impeachment by the House of Representatives and trial by the Senate for alleged high crimes and misdemeanors in office, or of the causes that led to it. Yet it was one of the most important and critical events, involving possibly the gravest consequences, in the entire history of the country. The constitutional power to impeach and remove the President had lain dormant since the organization of the Government, and apparently had never been thought of as a means for the...