The most shocking thing about Wednesday’s assault on the Capitol is that it happened. A mob of Trump supporters, some of them armed, stormed and vandalized both chambers of Congress, sending duly-elected lawmakers into hiding and interrupting the peaceful transition of power from one administration to the next.

That this was whipped up by the president — “We’re going to walk down to the Capitol and we’re going to cheer on our brave senators and congressmen and women and we’re probably not going to be cheering so much for some of them” — makes it an actual attack on the separation of powers: an attempt, by the executive, to subvert the legislature by force and undermine the foundation of constitutional government.

Nearly as shocking as the attack itself has been the response from Congress. On Wednesday night, its members resumed their count of the electoral vote and certified Joe Biden as the next president of the United States. So far so good. But then they adjourned into recess. It was Thursday afternoon before the Democratic leadership — Speaker Nancy Pelosi and the soon-to-be Senate Majority leader, Chuck Schumer — called for the president’s removal. And even then, they urged the vice president, Mike Pence, to use the 25th Amendment to do it, with impeachment as a backstop.

This is backward. A physical attack on Congress by violent Trump supporters egged on by the president demands a direct response from Congress itself. Impeachment and conviction is that response. To rely on the executive branch to get Trump out of the White House is to abdicate the legislature’s constitutional responsibility to check presidential lawbreaking.

There’s also the question of those members of Congress, like Senators Ted Cruz of Texas and Josh Hawley of Missouri, who helped bring the president’s mob into fruition by backing the effort to contest and overturn the electoral vote, an effort they carried on even after the Capitol was breached and terrorized Wednesday. Even if it’s just a motion to censure, Congress needs to act.

The alternative — to go slow, or worse, to take no action at all — will only create a sense of impunity. And American history offers ample evidence of how impunity in the face of mob violence can lead to something much worse than the chaos and mayhem on Wednesday. As it is, five people have died as a direct result of the mob attack on the Capitol.

On Sept. 14, 1874, more than 3,500 members of the White League — a paramilitary force of ex-Confederates and Democratic partisans — seized control of the Louisiana state house in New Orleans, as well as the city hall and the arsenal. They aimed to depose Gov. William Pitt Kellogg, a Republican, and install his Democratic opponent from the previous election in 1872.

It almost worked. White Leaguers overwhelmed an opposing force of Black state militia (led by James Longstreet, a Confederate general turned staunch supporter of the state’s Reconstruction government), took control of the city and even held an inauguration for the man, John McEnery, who would lead a “redeemed” Louisiana. Within days, however, news of the coup reached Washington, where an enraged President Ulysses S. Grant ordered troops to New Orleans. Rather than fight a pitched battle for control of the city, the White League surrendered, allowing Kellogg to return as governor shortly thereafter.

There was no punishment for the men who planned this attempted coup. So there was no reason not to try again. After the 1876 election, the White League seized New Orleans for a second time, ensuring victory for Francis T. Nicholls, the Democratic candidate for governor, and effectively ending Reconstruction in the state.

Just as important, the White League became a model for others in the South who sought an end to “Negro rule” in their states. In 1875, “White-Line” Democrats in Mississippi began a campaign of terror ahead of an election for state treasurer. They targeted Republican officials for assassination, sparked riots where Black citizens were beaten and killed, and sent armed vigilantes to break up campaign meetings and drive Black voters away from the polls. “Carry the election peaceably if we can,” declared one Democratic newspaper editor in the state, “forcibly if we must.”

The next year, in South Carolina, white Democrats used a similar approach — violence, fraud and intimidation — to “redeem” the state from Republican control and to try to deliver its electoral votes to Samuel Tilden, the Democratic nominee for president.

The toppling of Reconstruction was not the inevitable result of white racism. It was contingent on any number of factors, with uncontrolled violence near the top of the list. The vigilantes and paramilitaries — the White Leagues and Red shirts — operated with virtual impunity as they beat, killed and terrorized Black voters and their Republican allies. They demonstrated, again and again, that the state was weak and could be challenged and taken.

Despite its violence, the mob on Wednesday was, in many respects, very silly. Once inside the Capitol, they took selfies with police and posed for photos with each other. There were livestreams and a few people even wore costumes. They also took the time to grab souvenirs; a podium here, a letter from the Speaker’s office there. It was a big game, a lark.

But a lark can still have serious consequences. This particular mob successfully breached the Capitol in an effort, however inchoate, to install Donald Trump as president for a second time, against the will of the majority of voters and their electors. The mob failed to change the outcome of the election, but it showed the world what was possible. If the mob and its enablers — the president and his allies — walk away unpunished, then the mob will return.

Again, five people are dead who were alive when Wednesday began. Next time, it might be dozens. Or hundreds. Next time, our government might not bounce back so easily. Here, Congress doesn’t need courage. It just needs a sense of self-preservation.

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