Final answer:
Preston Brooks became famous for his involvement in the caning of Charles Sumner, a violent incident that occurred during a speech by Sumner criticizing proslavery legislators.
Step-by-step explanation:
Preston Brooks became famous for his involvement in the caning of Charles Sumner. Sumner gave a speech in which he criticized proslavery legislators, including Preston Brooks' relative. In response, Brooks assaulted Sumner with a cane, causing him to become unconscious and bloody. This incident, known as the "Caning of Sumner," highlighted the increasing tension and hostility between the North and the South regarding the issue of slavery in the 1850s.