https://en.wikipedia.org/wiki/Preston_Brooks

Brooks [a slavery advocate Congressman] confronted Sumner [an abolitionist Congressman], who was seated at his desk, writing letters. He said, “Mr. Sumner, I have read your speech twice over carefully. It is a libel on South Carolina, and Mr. Butler, who is a relative of mine.” As Sumner began to stand up, Brooks hit Sumner over the head several times with his cane, made of thick gutta-percha with a gold head. Sumner was trapped under the heavy desk (which was bolted to the floor), but Brooks continued to strike Sumner until Sumner wrenched the desk from the floor in an attempt to escape.[2]: 9  By this time, Sumner was blinded by his own blood. He staggered up the aisle and collapsed unconscious.[2]: 9  Senator John J. Crittenden, Representative Ambrose Murray (R-NY), and others attempted to restrain Brooks before he killed Sumner but were blocked by Keitt, who brandished a pistol and shouted at the onlookers to leave Brooks and Sumner alone.[2]: 9 [24] Brooks continued beating Sumner until the cane broke, then quietly left the chamber with Keitt and Edmundson.[2]: 10  Brooks required medical attention before leaving the Capitol, because he had hit himself above his right eye with one of his backswings.[2]: 10

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American Party Congressman Anson Burlingame publicly humiliated Brooks in retaliation by goading Brooks into challenging him to a duel, accepting, and then watching Brooks back out.[29] After Burlingame made provocative remarks, Brooks challenged Burlingame, stating he would gladly face him in any “Yankee mudsill” of his choosing.[30] Burlingame, a well-known marksman, eagerly accepted, choosing rifles as the weapons and the Navy Yards in the border town of Niagara Falls, Canada, as the location to circumvent the U.S. ban on dueling.[29] Brooks, reportedly dismayed by both Burlingame’s enthusiastic acceptance and reputation as a crack shot, backed out by citing unspecified risks to his safety if he was to cross “hostile country” (the Northern states) to reach Canada.[29][31]