Senator Charles Sumner (pictured) was assaulted by Representative Preston Brooks in the United States Senate chamber in retaliation for a speech in which Sumner fiercely criticized slaveholders.

Charles Sumner was an American lawyer and statesman who represented Massachusetts in the United States Senate from 1851 until his death in 1874. Before and during the American Civil War, he was a leading American advocate for the abolition of slavery. He chaired the Senate Foreign Relations Committee from 1861 to 1871, until he lost the position following a dispute with President Ulysses S. Grant over the attempted annexation of Santo Domingo. After breaking with Grant, he joined the Liberal Republican Party, spending his final two years in the Senate alienated from his party. Sumner had a controversial and divisive legacy for many years after his death, but in recent decades, his historical reputation has improved in recognition of his early support for racial equality.

The caning of Charles Sumner, or the Brooks–Sumner Affair, occurred on Thursday, May 22, 1856, in the United States Senate chamber, when Representative Preston Brooks, a pro-slavery Democrat from South Carolina, used a walking cane to attack Senator Charles Sumner, an abolitionist Republican from Massachusetts. 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. The beating nearly killed Sumner and contributed significantly to the country's polarization over the issue of slavery. It has been considered symbolic of the "breakdown of reasoned discourse" and willingness to resort to violence that eventually led to the Civil War.

Preston Smith Brooks was an American slaver, politician, and member of the U.S. House of Representatives from South Carolina, serving as a member of the Democratic Party from 1853 until his resignation in July 1856 and again from August 1856 until his death.