About 150 years ago, as Congress prepared to impeach President Andrew Johnson, someone discovered two bottles of what seemed like nitroglycerin in a Senate passageway. Hysterical politicians fled the building—until some bold newspaperman swigged the liquid. It was just bourbon.
The incident provided a powerful metaphor for the way impeachment turned a substance politicians could usually handle into something highly explosive. After months of drama, Lincoln’s former secretary John Hay concluded: “Impeachment is demonstrated not to be an easy thing. The lesson may be a good one some day.” The lesson, as good in 2017 as it was in 1868, is that removing a president is an ugly process, which can dangerously inflame tensions in an already divided nation.
There were, in the late 1860s, real fears that impeachment could spark a second Civil War. That rebellion was barely over, and posed a number of unanswered questions. What did the nation owe to millions of freed slaves? How should the federal government treat Confederate leaders and seceded states? What should northerners do about the atrocious outbreaks of racist violence unfolding in cities like New Orleans and Memphis?
Things were little calmer in Washington. A victorious, sometimes-cocky, Republican Party controlled more than three-quarters of both houses of Congress. Yet in the White House sat Andrew Johnson, put into power not by a popular vote, but by Lincoln’s assassination. And Johnson, it was painfully clear, was hostile to blacks, lenient with rebels, and hell-bent on fighting Congress.