At first intending to challenge Sumner to a duel, Brooks consulted with fellow South Carolina Rep. Laurence M. Keitt on dueling etiquette. Keitt instructed him that dueling was for gentlemen of equal social standing, and suggested that Sumner occupied a lower social status comparable to a drunkard due to the supposedly coarse language he had used during his speech. Brooks thus decided to attack Sumner with a cane.
Two days after the speech, on the afternoon of May 22, Brooks confronted Sumner as he sat writing at his desk in the almost empty Senate chamber. Brooks was accompanied by Keitt and Henry Edmundson of Virginia. Brooks 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 began beating Sumner with his thick gutta-percha cane with a gold head. Sumner was trapped under the heavy desk (which was bolted to the floor), but Brooks continued to bash Sumner until he ripped the desk from the floor. By this time, Sumner was blinded by his own blood, and he staggered up the aisle and collapsed, lapsing into unconsciousness. Brooks continued to beat Sumner until he broke his cane, then quietly left the chamber. Several other senators attempted to help Sumner, but were blocked by Keitt who was brandishing a pistol and shouting “Let them be!” (Keitt would be censured for his actions and later died of wounds in 1864 fighting for the Confederacy during the Civil War.)
Sumner was unable to return to his Senate duties for more than three years while he recovered. He later became one of the most influential Radical Republicans throughout the conduct of the Civil War, and on through the early years of Reconstruction.
(from Wikipedia)
Concerning the Thurmond-Yarborough bout, in 1964 Yarborough tried to drag Thurmond to his committee seat to vote on Civil Rights legislation. It was a mistake.
Legend has it that Brooks later received many gifts of replacement canes.