Judging by the comments of partisans invested in the outcome, Donald Trump’s impeachment was either a historic moment of glory for the House of Representatives or an unprecedented abuse of congressional power. The history of presidential impeachment, however, tells a different story. Trump’s impeachment was, if not predictable, certainly not surprising—even without being telegraphed by the “Resistance” for the past three years.

Impeachment history is admittedly meager. Two previous presidents were impeached by the House (Andrew Johnson and Bill Clinton); a third was driven from office by the certainty of impeachment and probability of removal (Richard Nixon). Johnson was charged with disrespecting Congress and violating the 1867 Tenure in Office Act; Nixon with obstruction of justice, abuse of power, and failure to comply with congressional subpoenas; Clinton with obstruction of justice and perjury. Although the specific offenses differed, four political factors hold these three cases together. Trump’s shares them.

The first and most obvious factor was opposition party control of the House. Johnson, though Abraham Lincoln’s vice president, was a pro-Union Democrat from Tennessee, added to Lincoln’s ticket as a gesture of unity. Congressional Republicans certainly didn’t consider him one of their own. Republican president Nixon faced a heavily Democratic House; Democratic president Clinton a solidly Republican one. Divided government, however, has become the norm since the 1950s; impeachment, though more common than before, is still (relatively) rare. An opposition House seems a necessary, but insufficient, condition for impeachment.

The second factor uniting the cases was a sense by the president’s opponents that he lacked electoral legitimacy. Johnson wasn’t elected president at all. Nixon won in 1968 with 43.4 percent of the national popular vote to Hubert Humphrey’s 42.7, then by a landslide in 1972—but the Watergate scandal, including revelations of dirty tricks and campaign finance violations, sullied that victory. Clinton never won a popular vote majority, gaining office with 43 percent in 1992 and 49.2 percent four years later, with the latter contest also accompanied by campaign finance irregularities.

Third, the president’s opponents thought his accession to the presidency a fluke, and him, in some ways, a usurper. Johnson became president as a result of the first presidential assassination in U.S. history. Nixon and Clinton gained office after an extended period in which the other party dominated presidential elections. Democrats had won seven of nine presidential votes before 1968; Republicans had prevailed in five of six elections leading up to 1992. It’s little exaggeration to say that in those cases the president’s opponents saw him as an interloper temporarily camping out in an office naturally belonging to them.

Finally, a large portion of the American public believed Johnson, Nixon, and Clinton fundamentally unfit for office from the start. As Stephen F. Knott discusses in The Lost Soul of the American Presidency (2019), Johnson made no friends with his drunkenly incoherent and demagogic vice presidential inaugural address. House Republicans had already tried to impeach him once, before succeeding in 1868. Indeed, congressional Republicans passed the Tenure in Office Act in hopes Johnson would violate it and strengthen the grounds for impeachment. For their parts, Nixon and Clinton came into office under significant ethical clouds. Nixon had long before acquired the nickname “Tricky Dick,’ while Clinton was rewarded with the moniker “Slick Willie” for his conduct in Arkansas. Overall, Republicans thought Clinton a deeply dishonest, pot-smoking, draft-dodging, skirt-chasing hippie.

These four factors were crucial complements to the proximate causes of impeachment. This can be understood by examining a couple of recent cases of non-impeachment. Ronald Reagan wasn’t impeached over Iran-Contra, a scandal involving the president’s sale of weapons to Iran despite congressional prohibition—proceeds of which were transferred to the anti-communist contra resistance in Nicaragua, which Congress had also prohibited. Barack Obama was not impeached over illegalities and abuses of power, including gun transfers to Mexican drug cartels (Operation Fast and Furious), the frequent use of executive orders to vitiate laws passed by Congress, and the use of the IRS to suppress political opponents during his reelection campaign.

Both Reagan and Obama (after 2010) faced an opposition House, but none of the other factors examined above. Obama won his elections with solid majorities; Reagan won 1980 by a landslide and 1984 by a bigger landslide. There was no serious question about either man’s electoral legitimacy (though Obama’s IRS scandal might have produced some such questions if the media had been more interested in following it). Neither Reagan nor Obama could be regarded as a fluke—they were preceded by the flukes Nixon and Clinton. A Republican winning in 1980 and 1984 was no longer a novelty, nor was a Democrat in 2008 and 2012. And, although both Reagan and Obama had bitter foes, neither entered the presidency reviled by millions as a moral stain on the office.

Of course, neither Reagan nor Obama should necessarily have been impeached. Reagan’s actions, for example, were arguably defensible, entwined in reasons of state, and it was never clear if he approved the transfer to the contras. The point is that the accusation at issue—whether disrespecting congressional prerogatives, using power for personal political gain, or stretching or breaking the law—is never more than one piece of the impeachment puzzle. The other pieces form the political context through which the House majority and the broader public perceives accusations. Nixon’s attempt to use the IRS to punish opponents was actually part of an impeachment article passed by the House Judiciary Committee in 1974; a questionable Ukrainian phone call by Reagan or Obama would probably not have resulted in impeachment.

Along these lines, Donald Trump stands much closer to the impeached than to the not-impeached. The House is controlled by the opposition party, newly-elected and dominated by a base of left activists. Trump’s election was immediately questioned, as he won in the Electoral College but trailed Hillary Clinton by three million votes nationwide. Trump not only lacked a popular vote majority, he lacked a plurality. Robert Mueller’s seemingly interminable investigation and the multiple leaked intelligence reports about Russian interference in 2016 added to the perception that Trump’s election was tainted—a perception undimmed for many even after Mueller found no evidence of “collusion” and the so-called “Steele Dossier” was discredited.

Trump was elected after Democrats won four of the previous six elections (and led in the popular vote in five of six), in an election nearly no one expected him to win. He was the first president in U.S. history to have no political or military experience, and the first to ride a Twitter wave of free media to the White House. He led his opponent in national polls for no more than a few days and had trailed badly in electoral vote estimates. Democrats had come to believe that the White House was theirs, and Hillary Clinton’s coronation a mere formality. If Johnson, Nixon, and Clinton could be called flukes, certainly Trump could, too.

Not least, Trump came to office already seen by vast swaths of the country—including many of his own voters—as unfit for the presidency by character and temperament. Exit polls showed that only one-third of voters answered “yes” when asked whether Trump was honest and trustworthy or had the temperament to be president; one in five who said “no” voted for him anyway. A lifetime of bankruptcies, affairs, and braggadocio set the stage, and a campaign of serial prevarications and insults culminated a month before election day, when his campaign nearly imploded with the Access Hollywood tape’s release, leading dozens of Republican officeholders to revoke their endorsements.

There is one significant contextual difference between Trump and Johnson, Nixon, and Clinton. When the latter three faced impeachment, the opposition party had a majority in the House and Senate. There was no guarantee of a two-thirds Senate vote—indeed, Nixon resigned before the case went to the Senate and the other two cases failed to receive the votes for removal. But the House could at least believe its case would be seriously considered, and its allies would control the proceedings. Trump is in the relatively enviable position of having his own party in charge in the Senate—if anyone is ever really in charge in the Senate. For the House to send an impeachment to a Senate predisposed to be friendly to the president is an unprecedented gambit—a stroke of either boldness or insanity. That it presented unforeseen complications is now apparent, even (or especially) to Speaker Nancy Pelosi.

In important respects, though, Trump’s impeachment fits the pattern of previous presidential impeachments. The specific charges differ, but it’s clear that this impeachment is not about specific charges. Like the other cases, Trump’s impeachment is grounded in a deeper and older perception that the president should simply not be president. His may have been an impeachment in search of a rationale, but to some degree they all were. Prognosticating is risky, but one can easily imagine that future historians will conclude Trump’s impeachment was neither historic nor unprecedented, but utterly ordinary.