The assault upon Mr. Sumner, while here seated at his Senatorial desk, May 22, 1856, was of a more serious nature and more to be regretted, than the quarrel—however serious its aspect—between Mr. Benton and Mr. Foote. A committee of investigation was appointed the next day, and on May 28th it reported the assault a breach of the privilege of the Senate, but held that the offense could be punished by the House of Representatives only, of which Mr. Brooks, the assaulting party, was a Member. Upon this report being sent to the House, that body appointed a select committee to investigate the case, to which the report of the committee of the Senate was referred May 29th. The House committee held the assault to be a breach of the privilege of the House, as a coordinate branch, and recommended expulsion. The resolution, however, failed of the necessary two-thirds vote, though on the same day, July 14, 1856, Mr. Brooks announced his resignation. He was fined $300 by the court in Washington; but his reelection to Congress, from South Carolina, without opposition, followed immediately.

The Senate committee in its investigation found that Senators Toombs, Pearce and Crittenden were seated in their respective chairs just preceding the affair. During the occurrence, Mr. Crittenden was observed near the parties, evidently striving to terminate the assault. Mr. Keitt also, a Member of the House from South Carolina, was seen to approach the parties, presumably with the same intention. . In his testimony before the committee, Joseph H. Nicholson, an eye-witness, gave the following lucid account of the unfortunate occurrence :

"On Thursday last, the 22nd of May, instant, a few moments after the adjournment of the Senate, I retired, as usual, to my desk in one of the offices of the Secretary of the Senate. After the lapse of a brief period I returned to the Senate Chamber to request the assistant doorkeeper (Mr. Holland) to have a piece of money changed for me. After seeking the doorkeeper and communicating my wish to him, I was walking down the main aisle of the chamber, when I observed the Hon. Mr. Brooks, of South Carolina, sitting at the desk of Senator Pratt. I saluted him, ' How is Col. Brooks to-day?' He responded, 'Well, I thank you,' and beckoning to me he added, 'Come here, Nicholson.' I advanced, and placing myself in Senator Bayard's chair, near which, on my right, Maj. Emory, of the United States Army, was standing, and with whom I had been conversing a few minutes before, Col. Brooks remarked to me in his usual tone of voice, and without the slightest show of inquietude, 'Do you see that lady in the lobby?' Turning round and observing a lady sitting on the lounge at a short distance from us, I said, ' Yes.' Col. B. said, ' She has been there for some time ; what does she want ? Can't you manage to get her out ?' Thinking that Col. B. was only indulging a momentary whim, I jocosely replied, 'No; that would be ungallant ; besides, she is very pretty.' Col. B., turning round, and looking at the lady, said, 'Yes ; she is pretty, but I wish she would go.' At this moment, the changed money was brought to me by one of the pages, and almost at the same moment Maj. Emory inquired, ' Who was that gentleman you were conversing with ?' I had scarcely said ' Col. Brooks, of South Carolina, a very clever fellow,' when observing Col. Brooks advancing in front of us, and towards, as though about to speak to, Senator Sumner, who was sitting at his desk apparently engaged in writing, or with papers before him, I cannot be positive which ; I voluntarily attempted to call Maj. Emory's attention to the fact, for I was much surprised to see a South Carolina Representative in the act of approaching to speak to Senator Sumner after the speech delivered by the latter the two previous days but one in the Senate. But before 1 could attract Maj. Emory's attention or express surprise, I saw Col. Brooks lean on and over the desk of Senator Sumner, and seemingly say something to him, and instantly, and while Senator Sumner was in the act of rising, Col. Brooks struck him over the head with a dark-colored walking cane, which blow he repeated twice or three times, and with rapidity.

" I think several blows had been inflicted before Senator Sumner was fully in possession of his locomotion, and extricated from his desk, which was thrown over or broken from its fastenings by the efforts of the Senator to extricate himself. As soon as Senator Sumner was free from the desk he moved down the narrow passageway under the impetuous drive of his adversary, with his hands uplifted as though to ward off the blows which were rained on his head with as much quickness as was possible for any man to use a cane on another whom he was intent on chastising. The scene occupied but a point of time—only long enough to raise the arm and inflict some ten or twelve blows in the most rapid succession—the cane having been broken in several pieces. All the while Senator Sumner was holding his hands above his head, and turning and tottering, until he sank gradually on the floor near Senator Collamer's desk, in a bleeding and apparently exhausted condition. I did not hear one word, or murmur, or exclamation, from either party until the affair was over. Such was the suddenness of the affair, the rapidity of its execution, the position of persons in the chamber, and the relative positions of the chairs and desks, that, although several persons (myself among them) quickly advanced to the spot where the parties were engaged, it was not in the power of those present to have separated Col. Brooks, or to have rescued Senator Sumner, so as to have prevented the former from accomplishing his purpose. Such was the conclusion of my judgment at the moment of the occurrence, and such it is now".

At the same investigation, Governor Brown of Mississippi testified that Mr. Brooks had in this way spoken to him of the affair : "Regarding the speech (of Mr. Sumner) as an atrocious libel on South Carolina and a gross insult to my absent relative (Judge Butler) I determined, when it was delivered, to punish him for it. To-day I approached him, after the Senate adjourned, and said to him, ' Mr. Sumner, I have read your speech carefully, and with as much calmness as I could be expected to read such a speech. You have libeled my State and slandered my relation, who is aged and absent, and I feel it to be my duty to punish you for it'; and with that I struck him a blow across his head with my cane, and repeated it until I was satisfied. No one interposed, and I desisted simply because I had punished him to my satisfaction".