We all know the story.

On a mild April night, President and Mary Lincoln attended the final performance of the popular comedy, “Our American Cousin,” at Ford’s Theater. Lincoln, by all accounts was in a light, blissful mood. A week earlier Confederate forces commanded by Robert E. Lee had surrendered at Appomattox Courthouse, Virginia, and except for some dust ups, the Civil War had ceased. We also know that John Wilkes Booth, and fellow conspirators plotted to kill, not only the President, but the whole order of presidential succession; Vice President Andrew Johnson, Secretary of State William Seward, etc . . . but only Booth followed through with that night’s violence.

Andrew Johnson took office in a whirlwind of shifting circumstances. In the year up to President Lincoln’s death a notable power struggle had taken shape between the President and Congress. America had never before endured a civil war, and the path to reunion had never been trod. As President, Lincoln believed the power to restore the Union lay in the executive branch—through presidential pardon. But an emerging faction in the Republican Party, called the Radicals saw the issue differently. These men operated from the premise that the Confederate States had indeed left the Union—committed political suicide at secession—and had to petition Congress for readmission. (Congress approves statehood). And this new president, Andrew Johnson, was determined to follow through with Lincoln’s policies.

Unfortunately, Johnson was by temperament, nothing like Abraham Lincoln. Where Lincoln had a capacity to understand the views of his opponents, and utilize humor and political savvy, Johnson could not. Of prickly character, Andrew Johnson entered the White House possessed by deeply-held rancor against both the South’s Planter Class, and newly freed blacks. This new Chief Executive intended to restore the Union through the use of pardons, then govern through his strict interpretation of the Constitution. Johnson had no use for Radical Republicans, nor their extreme pieces of legislation. Every bill passed through the House and Senate found a veto waiting at Johnson’s desk, including the 1866 Civil Rights Act, and the adoption of the Freedmen’s Bureau. Congress promptly overrode Johnson’s vetoes.

Reconstruction began with a vicious power struggle. And much of the tumult came from Andrew Johnson’s inability to grasp the transformation Civil War had brought to America. While the new president aimed to keep government limited, the Radicals and their supporters knew the bloody struggle had to mean something more—America had fundamentally changed. Nearly 700,000 dead, the emancipation of slavery, the murder of Father Abraham, and a “New birth of Freedom” had heralded an earthquake of change.

But Johnson was blind to this reality, seeing only an overreaching Congress, (Tenure of Office Act) and Constitutional amendments that had gone too far. And so it was a rigid and stubborn Andrew Johnson who eventually found himself impeached by a fed-up House of Representatives. Johnson holding on to his broken presidency by a single Senate vote.

There have been other eras in America’s past that fomented rapid changes. The Revolution to the Constitutional period, the First World War into American isolation, the Vietnam War stirring up protest and social change. All concluding with reactionary presidencies. No less occurred with the 2016 election of Donald Trump.

2008 to 2016 witnessed social change of a new order. Administered by America’s first African-American President, Barack Obama, liberty reached further, bringing about change where once-closeted American’s hid. Gay marriage became the law of the land, upheld by the Supreme Court in Obergefell V Hodges. The trans community found their champion in Bruce, now Caitlin Jenner. Health care became available to those caught in relentless poverty and preexisting conditions. Undocumented young people were transformed into “Dreamers.” And though he didn’t take the Right’s guns, President Obama did successfully direct the mission to nab Osama bin Laden, America’s most wanted man.

So when former students began sending horrified texts to me, their old history teacher on election night, 2016, I gave the only explanation history provided. The Obama years introduced change to America that reactionaries could not stomach. (And yes, racism is certainly a large part of the equation).

So now we deal with a Donald Trump presidency. But, Mr. Trump would be wise to acknowledge and accept what has transpired in the last eight years. The thing about expanding the ‘blessings of liberty,’ is no one is willing to give them back. When push comes to shove, the new president may find himself facing the fate of Andrew Johnson.

Gail Chumbley is the author of River of January and River of January: Figure Eight. Also on Amazon.