A mob of Trump supporters stormed the US Capitol on Wednesday, leading to evacuations of lawmakers and at least four deaths — a surreal, embarrassing scene that felt like a predictable finale to this whole sordid era.

There’s a debate about whether to call the events of Wednesday a “coup” (before this attack, I was skeptical of throwing that term around; now I’m not), but one thing is certain: The Capitol being breached has not happened before in American history. There was a British raid on the Capitol during the War of 1812, but those were foreign troops, not American citizens.

A monumental question is whether we’re on the brink of something much worse. Was this just a flash of violence incited by a reckless president — or the start of a very ugly and dangerous period of American history, something akin to the 1850s before the Civil War?

To think this through, I reached out to Nathan Kalmoe, a political scientist at Louisiana State University and the author of With Ballots and Bullets: Partisanship and Violence in the American Civil War. Kalmoe’s work focuses on the relationship between partisanship and violence throughout American history. So I asked him to put this moment in context and compare it to previous eras of chaos in American politics. What I really wanted to know is whether this strikes him as the end of something nasty — or the start of something far nastier.

A lightly edited transcript of our exchange follows.

Sean Illing

In the history of American politics, how unprecedented is what we witnessed today? What are the closest parallels?

Nathan Kalmoe

Most folks don’t realize just how many historical parallels we have for this moment, though none are recent. Our party identities are largely aligned by race and religion, similar to how they did in the second half of the 19th century, which, not coincidentally, was full of racial-partisan violence. Political scientist Lily Mason’s work on public opinion shows that those alignments supercharge partisan animosities.

One parallel within Congress itself was in the 1850s, just before the Civil War. That involved dozens of violent attacks and fights with weapons drawn among members of Congress, which historian Joanne Freeman has written eloquently about.

The Civil War was the most extreme example of election rejection, by Southern Democrats against Lincoln’s election, though they did not claim any fraud to justify their rebellion. That violence ultimately killed three-quarters of a million Americans. What many people don’t realize is that there were substantial levels of violent partisanship in the North during that time, including insurrection plots by high-level Democrats.

Violence nearly broke out after the contested 1876 election, with Democrats calling for the coronation of their own candidate: “Tilden or blood!” President Grant called in the military to defend the US Capitol, but it was not ultimately besieged.

Of course, Reconstruction and Jim Crow were full of racial violence, which was also partisan violence, given the alignment of race and party in the South. That period included thousands of murders by white supremacists who killed Black Republicans and their allies in efforts to intimidate voters and election officials. There were even attempts to overthrow state and local governments following elections in Louisiana and North Carolina.

A more recent case with opposite moral valence was when armed Black Panthers took over the California state legislature in 1967.