William Henry Seward (May 16, 1801 – October 10, 1872) was United States Secretary of State from 1861 to 1869, and earlier served as Governor of New York and United States Senator. A determined opponent of the spread of slavery in the years leading up to the American Civil War, he was a dominant figure in the Republican Party in its formative years. Although regarded as the leading contender for the party's presidential nomination in 1860, he was defeated by Abraham Lincoln.