Charles Sumner was an American statesman and United States Senator from Massachusetts. As an academic lawyer and a powerful orator, Sumner was the leader of the anti-slavery forces in the state and a leader of the Radical Republicans in the U.S. Senate during the American Civil War. During Reconstruction, he fought to minimize the power of the ex-Confederates and guarantee equal rights to the freedmen. He fell into a dispute with President Ulysses Grant, a fellow Republican, over the control of Santo Domingo leading to the stripping of his power in the Senate and his subsequent effort to defeat Grant's re-election.
Sumner changed his political party several times as anti-slavery coalitions rose and fell in the 1830s and 1840s before coalescing in the 1850s as the Republican Party, the affiliation with which he became best known. He devoted his enormous energies to the destruction of what Republicans called the Slave Power, the influence over the federal government by Southern slave owners who sought the continuation and expansion of slavery.