Born in Lancaster, Ohio, Sherman later moved to Mansfield, where he began a law career before entering politics. Initially a Whig, Sherman was among those anti-slavery activists who formed what became the Republican Party. He served three terms in the House of Representatives. As a member of the House, Sherman traveled to Kansas to investigate the unrest between pro- and anti-slavery partisans there. He rose in party leadership and was nearly elected Speaker in 1859. Sherman was elevated to the Senate in 1861. As a senator, he was a leader in financial matters, helping to redesign the United States' monetary system to meet the needs of a nation torn apart by civil war. He also served as the Chair of the Senate Agriculture Committee during his 32 years in the Senate. After the war, he worked to produce legislation that would restore the nation's credit abroad and produce a stable, gold-backed currency at home.