A founding member of the Republican Party and one of its most energetic antislavery voices, the public life of Senator William Pitt Fessenden touched on all the major controversies confronting the nation between the time of the debates over slavery in the territories until the failure of Reconstruction. Born out of wedlock in Boscawen, N.H., on October 16, 1806, Fessenden graduated with a degree in law from Bowdoin College in 1827, and was admitted to the bar in the same year. Shortly thereafter, he embarked on a political career, winning election as a Whig representative to the Maine legislature for several terms beginning in 1831, and to Congress for one term in 1840. He was a conservative by nature, but was galvanized into the radical camp on the issue of slavery by his experience during his first term in Congress. Thereafter, he became an important figure in furthering the spread of abolitionist sentiment in his home state, and was in turn benefited by its growth when he decided to return to public office in 1853.
Fessenden won election to the Senate as an antislavery Whig, and took his seat in March, 1854, at one of the most difficult moments in American political history. During his first term, Fessenden became embroiled in the debates over the extension of slavery to the territories, the furor over "Bleeding Kansas," and the fallout over John Brown's raid on Harper's Ferry. His powerful speech in opposition to the Kansas-Nebraska bill vaulted him to national prominence, and following his switch to the Republican Party in 1856, he became one of the most visible and voluble political antagonists of the Buchanan administration, and one of the staunchest figures in rejecting compromise with slavery, secession, and rebellion. Fessenden remained firm in his views despite personal loss: during the war, two of his sons, Francis and James Deering, rose to the rank of general in the Union army, and a third, Samuel, was killed in action at the Second Bull Run.
During his tenure in the Senate, Fessenden earned a reputation as a skilled debater and as an expert on public finance. As a result, he was appointed Secretary of the Treasury during Lincoln's second administration, replacing Salmon Chase. After returning to his seat in the Senate following the accession of Andrew Johnson, he became Chair of the Joint Committee on Reconstruction, and opposed the administration as one of the prime exponents of a radical Reconstruction policy. Fessenden believed that given the totality of the federal victory over the Confederacy, conservative plans for Reconstruction like Johnson's were absurd, and he argued firmly that it was the responsibility of the Congress to set Reconstruction policy, not of the Executive. Yet Fessenden's views became increasingly conservative after 1866, and he opposed efforts to impeach Johnson on the principle that Johnson had not technically broken the law. Fessenden's was one of the very few Republican votes for acquittal. His role in the impeachment proceedings, along with his opposition to some features of the confiscation bill and other measures, led to a break with leaders of the radical faction, and a consequent reduction in his power in Congress. Throughout, Fessenden felt that he was acting from a principle of justice, regardless of the opinions of his colleagues, and refused to relent. He continued to serve in the Senate until his death in 1869.