The attack was in retaliation for an invective-laden speech given by Sumner two days earlier in which he fiercely criticized slaveholders, including pro-slavery South Carolina Senator Andrew Butler, a relative of Brooks.

[3]Sumner's rhetoric was largely directed at the authors of the Act, Senators Stephen A. Douglas of Illinois and Andrew Butler of South Carolina.

Regarding Butler, Sumner said: The senator from South Carolina has read many books of chivalry, and believes himself a chivalrous knight with sentiments of honor and courage.

Let her be impeached in character, or any proposition made to shut her out from the extension of her wantonness, and no extravagance of manner or hardihood of assertion is then too great for this senator.

[4]Sumner also mocked Butler's speaking ability, which had been impeded by a recent stroke:[5] [He] touches nothing which he does not disfigure with error, sometimes of principle, sometimes of fact.

Williamjames Hoffer states that "It is also important to note the sexual imagery that recurred throughout [Sumner's] oration, which was neither accidental nor without precedent.

Keitt told him that dueling was for gentlemen of equal social standing, and that Sumner was no better than a drunkard, because of the supposedly coarse language he had used during his speech.

[12] Two days later, on the afternoon of May 22, 1856, Brooks entered the Senate chamber with Keitt and another ally, Representative Henry A. Edmundson of Virginia.

He staggered up the aisle and, arms outstretched, vainly attempted to defend himself, but that made him an even larger and easier target for Brooks, who continued to beat him across the head, face, and shoulders "to the full extent of [my] power".

[22] Representatives Ambrose S. Murray and Edwin B. Morgan were finally able to intervene and restrain Brooks, at which point he quietly left the chamber.

[26] With the aid of Nathaniel P. Banks, the Speaker of the House, and Senator Henry Wilson, Sumner was able to travel by carriage to his lodgings, where he received further medical treatment.

[29][30] This portion of the cane eventually ended up at the Old State House Museum in Boston; it was worked to smooth the edges and finish, and then put on display.

"[33] William Cullen Bryant of the New York Evening Post, asked, "Has it come to this, that we must speak with bated breath in the presence of our Southern masters? ...

"[34] Thousands attended rallies in support of Sumner in Boston, Albany, Cleveland, Detroit, New Haven, New York, and Providence.

The Richmond Enquirer editorialized that Sumner should be caned "every morning", praising the attack as "good in conception, better in execution, and best of all in consequences" and denounced "these vulgar abolitionists in the Senate" who "have been suffered to run too long without collars.

[40] In reference to a rumor that Brooks might attack him in the Senate, Wilson told the press, "I have sought no controversy, and I seek none, but I shall go where duty requires, uninfluenced by threats of any kind.

[45] In fact, Sumner suffered head trauma that caused him chronic, debilitating pain for the rest of his life and symptoms consistent with what is now called traumatic brain injury and post-traumatic stress disorder; he spent three years convalescing before returning to his Senate seat.

[52] A motion for Brooks' expulsion from the House failed, but he resigned on July 15 in order to permit his constituents to ratify or condemn his conduct via a special election.

[60] Historian William Gienapp has concluded that Brooks' "assault was of critical importance in transforming the struggling Republican party into a major political force".

[64] The violence in Kansas and the beating of Sumner helped the Republicans coalesce and cohere as a party, which set the stage for their victory in the 1860 presidential election.

[65] During the 1856 lame-duck session of Congress, Brooks made a speech calling for the admission of Kansas "even with a constitution rejecting slavery".

[66][67] The caning was a motivating factor in the abduction and murder of five pro-slavery settlers by the abolitionist leader John Brown in the Pottawatomie massacre.