When House Majority Whip Steve Scalise, R-La., and four others were shot during baseball practice at a park in Alexandria, Va., on Wednesday morning, it was the third incident of violence involving legislators in recent weeks and by far the most extreme. On May 24 in Montana, only hours before being elected to the House, Greg Gianforte "body-slammed" Guardian reporter Ben Jacobs for asking a question about health care policy. Five days later, during an immigration policy protest in the Texas House, Republican Rep. Matt Rinaldi caused a scuffle when he confronted Latino members of the chamber about protesters in the gallery.

This is hardly politics as normal in America. But it's not unprecedented. Throughout the first half of the 19th century, legislative violence was far more common. State legislatures and Congress sporadically erupted into violence. Lawmakers assaulted each other during debate — in one case in Arkansas, resulting in a death. And occasionally, aggrieved citizens assaulted lawmakers.

During the 1840s and 1850s, Congress was ground zero for legislative violence because it was the epicenter of the nation's fraught slavery debate. In those two decades alone, there were scores of violent incidents in the House and Senate, including shoving matches, fistfights, guns and knives drawn, canings, and the occasional mass brawl.

The American public wasn't far removed from such happenings. Then, as now, there was widespread interest in Congress' work, and the press met the demand. This era marked the rise of a sensationalized, splashy style of journalism aimed at scoring points and selling papers, so congressional news was pumped full of passions, particularly in the all-powerful New York City papers — the period's equivalent of today's mainstream media.

Did this endanger congressmen? Some people wondered. During the struggle to forge a compromise over slavery in 1850, Rep. David Outlaw, a Whig from North Carolina, wasn't sure he was safe even in the Capitol. "In times of great excitement, as upon the slavery question, armed men might be admitted into this Hall," he worried. With hundreds of people milling about the Capitol, "in less than three minutes three hundred strangers" could rush into the House and bring "bloodshed and confusion" in their wake.

Outlaw had reason to worry: Congressmen had been attacked in the Capitol before. In 1844, the antislavery activism of former president and Rep. John Quincy Adams, Whig-Mass., drove one man to accost him in the lobby. "You are wrong, you are wrong, and I will kick you," said the attacker as he struck at Adams, who held his assailant off until he was arrested.

That same year, a Kentucky visitor got so excited by a brawl in the House — sparked by a Democrat who insulted Kentucky Whig Henry Clay — that he rushed into the melee and fired his pistol, hitting a Capitol police officer in the leg.

Arming members of Congress didn't help matters. It was all too easy to get hot-tempered during a fractious debate and pull a weapon. In 1850, when Sen. Thomas Hart Benton, D-Mo., lunged at Sen. Henry Foote, D-Miss., for insulting him, Foote responded by pulling a pistol and pointing it at Benton. In this case, nothing happened; the gun was taken from Foote, and there the matter ended. But the potential for bloodshed was real. Foote later said that he had tried to position himself to hit as few people as possible if he had fired.

In the late 1850s, congressional violence reached its peak. The caning of Sen. Charles Sumner, R-Mass., on May 22, 1856, is the most famous of the period's clashes, but far from the only one. Noteworthy among them was a mass rumble in 1858 between Republicans and Democrats, described by many as the first time that a group of Northerners confronted a group of Southerners "force against force." Members "fought in battalions," a reporter noted. "They did not go into a corner or a lobby to fight, or entangle themselves as heretofore, between chairs and desks." Rep. Thaddeus Stevens, R-Pa., dubbed Congress "a hell of legislation."

Congress had become a dysfunctional battleground of sectional distrust; the national government seemed unable to bridge divides. National political parties were splintering; new parties — chiefly, the Republican Party — were coming to life. The press played up the unrest to score points and sell papers, and the telegraph, coming into its own then, spread that message through the nation at breakneck speed. National institutions were faltering as a sectional crisis hit its stride. It was a recipe for disaster, as the Civil War would soon prove all too well.

There are clear echoes of this past in our present. Extreme political polarization. A dysfunctional Congress with seemingly unbridgeable divides. Splintering political parties. A splashy national media playing to its audience. News boomeranging around the country faster than ever before (on social media rather than by wire). Government instability on a massive scale, with norms of constitutional democracy and republican government being violated on a daily basis.

American faith in our national institutions is faltering. The threads of our civil society are fraying. Violence of all kinds is on the rise. And members of Congress are paying the price. Now, as in the 1850s, congressional violence is representative of our nation as a whole. We would be well-advised to heed this warning and tone down our rhetoric and outrage, for the good of the nation and of ourselves.

Joanne B. Freeman is a professor of history and American studies at Yale University, a co-host of the history podcast BackStory and author of "The Field of Blood: Congressional Violence and the Road to Civil War," to be published in April 2018. She wrote this article for the Washington Post.