Mr.Sumner's seat was in the outside row next to the railing, at the second desk to the right from the entrance and the main aisle.

Occupied with his work, Mr.Sumner did not notice Mr.
Brooks, sitting across the aisle to his left, and where in conversation with a friend he was manifesting his impatience that a lady seated near Mr.Sumner did not take her departure from the chamber.

Almost at that moment she arose and went out; quickly afterwards Brooks got up and advanced to the front of Sumner's desk.
The act attracted the attention of Brooks's friend; he was astonished, amid the bitterness of party feeling, to see a South Carolina Representative talk to a Massachusetts Senator.

His astonishment was quickly corrected.

Leaning upon the desk and addressing Sumner with a rapid sentence or two, to the effect that he had read his speech, that it was a libel upon his absent relative, and that he had come to punish him for it, Brooks began striking him on the head with a gutta-percha walking-cane, of the ordinary length and about an inch in diameter.
Surprised, blinded and stunned by the blows, Sumner's first instinct was to grapple with his assailant.