Confrontations between protestors and Republican Presidential candidate Donald Trump at his rallies have become routine this primary season. Unlike in past elections, where candidates ignored or played down episodic protestors, Trump has relished the opportunity to bait his hecklers and return the rhetorical fire. Rare as it may be for a presidential candidate or sitting President to engage in verbal combat or threats of violence with demonstrators, it is not unprecedented. Perhaps the most noteworthy example of a President wading into a vituperative mob happened in 1866, when President Andrew Johnson launched his famous speaking tour known as the Swing Around the Circle. Widely mocked by the press and by politicians of all stripes, Johnson’s descent into the politics of the street effectively sank his presidency.

Johnson’s problems started in December 1865, when Congress refused to seat representatives from the president’s reorganized southern state governments. Tensions between the executive and legislative branches escalated further in the spring and summer of 1866, when Congress overrode Johnson’s vetoes of the Civil Rights Act and the Freedmen’s Bureau Reauthorization Act, which were designed to counteract the notoriously discriminatory “Black Codes” passed by southern state legislatures. Soon Johnson began to lose the public as well as Congress. Horrific racial massacres in Memphis and New Orleans during the summer of 1866 made citizens blame Johnson for failing to protect African Americans. Even otherwise conservative Unionists who opposed radical measures to remake the American South on broadly egalitarian grounds began losing faith in Johnson’s stewardship of Reconstruction.

With the 1866 Congressional elections looming, an increasingly isolated Johnson decided to do something that no President had ever done before. He announced a speaking tour of cities across the North and West to woo public opinion to his side and stem the tide that was shifting toward the Republican Congress. Over the course of eighteen days in the late summer of 1866, Johnson traveled by rail to Baltimore, Philadelphia, New York, West Point and Albany before heading west to Buffalo, Cleveland, Toledo, Detroit and Chicago.

At first, on the northeasterly leg of the tour of the so-called Swing Around the Circle, enthusiastic crowds greeted Johnson. By the time he reached Cleveland, however, things turned sour, especially as journalists began noticing the repetitiveness of Johnson’s speeches. Indeed, if rail technology facilitated Johnson’s national tour, another technology–the telegraph–undermined it. Critics started planning to throw Johnson off his game by mocking his repetitive remarks, and the tactic worked. Johnson began to heckle back at the crowd. He compared himself to Jesus Christ and, when asked to hang Jeff Davis, he responded with reference to two Radical Republicans, “Why don’t you hang Thad Stevens and Wendell Phillips!” (Stevens was a sitting congressman.) Things degenerated from there, with Johnson even claiming at one point, “I don’t care about my dignity.”

Ironically, Johnson met with the most hostile reception along his return tour through the Lower North. Voters in that section of the country were presumably more sympathetic to his conservative Reconstruction plan, but from St. Louis on through Indianapolis, Louisville, Cincinnati, Pittsburgh and Harrisburg, the heckling actually grew louder, with crowds demanding to see General Ulysses Grant instead of Johnson. Increasingly, Johnson was accused of drunkenness and demagoguery, and of producing “street brawls.”

A newspaper correspondent in Indianapolis captured the cacophony of Johnson’s address there:

Johnson said, “FELLOW-CITIZENS [cries for Grant]: It is not my intention [cries of ‘Stop,’ ‘Go On!’] to make a long speech. If you give me your attention for a few minutes [cries of ‘Go on!’ ‘Stop!’ ‘No, no; we want nothing to do with traitors!’ ‘Grant!’ ‘Johnson!’ and groans], I would like to say to this crowd here to-night – [cries of ‘Shut up, we don’t want to hear from you!’ ‘Johnson!’ ‘Grant!’ ‘Johnson!’ ‘Grant!’]” The President paused a few moments and then retired to the balcony.

The disturbance at Indianapolis intensified after Johnson left the stage, with protestors smashing a “Johnson! Welcome the President!” placard with clubs. Then supporters and opponents alike fired pistol shots.

Notably, the press blamed Johnson more than the crowd for the disturbances. The Potter County (PA) Journal wryly remarked that “mobs, whether in Memphis, New Orleans or Indianapolis should be condemned by all good men.” But, it said, Johnson’s own logic in blaming Radicals for the racial violence in the two southern cities made Johnson himself culpable for inflaming the crowd in Indianapolis. Echoing calls from both conservatives and radicals, the Journal admonished Johnson, arguing that “if he would stay in the White House, keep his mouth shut, and not make a fool of himself, disgusting friend and foe alike with his drunken jabberings, there would be no one killed at his meetings, and the President of the United States might command some respect.”

The heckling revealed more than tension over the sensitive matter of Reconstruction. It also drew upon a decades-old tradition of street confrontation that had long defined America’s practice of democracy. At the same time, however, it challenged another familiar element of American popular politics: the notion that the President of the United States, as the head of state akin to a European king or emperor, was somehow supposed to be above the popular fray. Presidential candidates did not actively campaign for office (though Stephen Douglas broke that tradition briefly in 1860) and Presidents did not travel the country on speaking tours. The political fallout of the Swing Around the Circle proved disastrous for Johnson, as Republicans dominated the 1866 Congressional elections and promptly took command of the Reconstruction process.

Expectations that Presidents and presidential candidates will remain above the fray have continued to this day. Commentators, especially those within Trump’s Republican Party who have reacted with such alarm to Donald Trump’s heckler-baiting routine, are defending a time-honored tradition. As Andrew Johnson discovered in the fall of 1866, once a President or presidential candidate wades into the mob, it becomes almost impossible to regain the respect generally accorded holders of the highest office in the land.