By the beginning of the Civil War, Massachusetts Senator Henry Wilson had established himself as one of the leaders of the Republican party. Together with Abraham Lincoln and Henry B. Stanton, Wilson ranks as one of the three most important civilian figures that contributed to creating and sustaining the military. As Chairman of the Senate Military Affairs Committee, he introduced and succeeded in passing most of the necessary legislation to obtain and to support an army, including the Enrollment Act of 1863. Wilson, more than any other politician was responsible for influencing the successful passage of antislavery legislation during the Civil War years. Contemporary newspapers gave him the primary credit for abolishing slavery in the District of Columbia, which was the most important abolition step prior to the Emancipation Proclamation. When free Black men were admitted to the army, Wilson worked hard to obtain equal pay for them. Late in the war, he played a major role in the creation of the Freedmen's Bureau. Among his other legendary achievements, Wilson used his influential position to support Clara Barton, enabling her to aid wounded soldiers. He also introduced and succeeded in having passed legislation creating the Congressional Medal of Honor and establishing the National Academy of Science.

Already a leader of the Republican party when the Civil War began, Henry Wilson had distinguished himself as the most important Congressional figure on military and antislavery and pro-black legislation during the war. During the Era of Reconstruction, Wilson fought to protect the rights of the newly-freed slaves, but he was opposed to the severe punishment of Confederate leaders and initially tried to be conciliatory toward President Johnson's lenient policies. Soon Wilson joined others in promoting Congress's own Reconstruction program, including the 14th and 15th Amendments, the Military Reconstruction Acts, and the impeachment of the President. He became the Republican Party's most frequently-used campaign speaker. Long recognized as a spokesman for labor, he was also the foremost national politician promoting the cause of prohibition. He wrote the most authoritative three-volume work on the causes of the Civil War from the northern viewpoint. He was also a frequent contributor to the era's most influential religious periodical. In 1872, Wilson was rewarded for his political activities when he was nominated and elected as the country's vice-president.

This biography deals with the life of Henry Wilson, one of the most important figures of the middle third of the Nineteenth Century, up to the time of the Civil War. Among its concerns are the political antislavery movement, economic development, the rise of a working class politcian in an aristocratic-controlled state, prohibition, and Massachusetts state history.