As an academic lawyer and a powerful orator , Sumner was the leader of the antislavery forces in Massachusetts and a leader of the Radical Republicans in the United States Senate during the American Civil War working to destroy the Confederacy , free all the slaves , and keep on good terms with Europe .
He was a leader of the Radical Republicans in the United States Senate during the American Civil War . He worked to destroy the Confederacy , free all the slaves and keep on good terms with Europe .