The impeachment of Andrew Johnson in 1868 is a strange and compelling drama played out on the stage of a young nation barely at peace with itself. We may think we live in a divisive era today but it doesn’t hold a candle to post-Civil War America.

The story of Johnson’s journey to impeachment, told in a lucid and long-overdue reexamination by David O. Stewart in "Impeached: The Trial of President Andrew Johnson and the Fight for Lincoln’s Legacy," begins in 1864 when Lincoln decided to replace Hannibal Hamlin, his perfectly serviceable vice president, with Johnson, a Tennessean. Lincoln made the move in an effort to promote national unity. Johnson was a Democrat from a secessionist state, although he had stood loyally by the Union throughout the war. It was as if John McCain had tapped Joe Lieberman, or better yet, Nancy Pelosi.

But, alas, like many a self-proclaimed “uniter,” Johnson turned out to be anything but. Right from the start, there were problems. At his inauguration as second-in-command, Johnson was three sheets to the wind. Six weeks later, Lincoln was assassinated and Johnson became president.

Johnson was a Southerner, and as such, he was committed to a “states’ rights” prescription for national unity; one that would put him on a collision course with a Congress dominated by Northern Republicans, some of whom were quite radical in deed and name.

Thaddeus Stevens of Pennsylvania, for example, felt that since the South had lost the war it was now time to pay the piper. Under Reconstruction as envisioned by radical Republicans, the South would be born again – under terms dictated by the North. States below the Mason-Dixon line would be required to treat the newly freed slaves as full and equal citizens (even though many Northern states prohibited their own black residents from voting).

At the same time, Republicans didn’t favor allowing prominent Rebels to waltz back into key positions in state and federal government.

Johnson, on the other hand, adopted a “let bygones be bygones” approach to the war that took some 600,000 American lives. The Southern states, he believed, had technically never left the Union and he was quite comfortable with letting these contrarian entities reestablish government as they saw fit. He turned a blind eye to the violence that erupted against blacks and Unionists, including a massacre in his own state. Before leaving office, he granted amnesty to all of those who fought against the Union, including Jefferson Davis.

In 1866 many prominent Rebels were elected to Congress, including Alexander Stephens of Georgia, who had been vice president of the Confederacy and was under indictment for treason. Congress refused to seat him and the others. That meant that later in 1868, when Johnson faced impeachment charges, he was impeached and tried by a House of Representatives without Southern representation. (Johnson was impeached by the House but acquitted by a single vote in the Senate.)

Author Stewart, a prominent Washington, D.C., lawyer, documents this remarkable tale of political bloodletting with skillful aplomb and insight. His grasp of the legal complexities of presidential impeachment, such as what exactly constitutes “high crimes and misdemeanors,” is matched by a good eye for the human dimensions of this continuation of war by other means.

Johnson’s “crime” was that he tried to replace Edwin Stanton, his secretary of war, and in so doing violated the Tenure of Office Act, a law enacted by Congress several months earlier that prohibited the president from firing his own Cabinet members.

Stewart’s brief, ably argued, is that Johnson’s impeachment has long been in need of a second historical opinion. Conventional wisdom has it that our 17th president was merely trying to carry out Lincoln’s legacy and to bind up the nation’s wounds. Conversely, the big bad Congress was out of control, bent upon an unconstitutional power grab and inflicting blind vengeance on the prostrate South. John F. Kennedy took this tack in “Profiles in Courage,” proclaiming the vote of Republican Sen. Edmund G. Ross against impeachment to be singularly heroic.

Stewart terms this a “myth,” asserting that cold cash and future patronage, not courage, likely motivated Ross and six other breakaway Republicans to side with Johnson.

There is no doubt that Johnson’s impeachment and acquittal were peculiar. He was unquestionably a ghastly, cantankerous president, but the main charge against him was that he broke an unclearly worded law that had been enacted over his veto. (The Tenure of Office Act was repealed in 1887.)

It was an unhappy time for the entire nation. When Johnson finally left the stage in March 1869, he mercifully declined to attend Ulysses S. Grant’s inauguration.