An award-winning scholar uncovers the guiding principles of Lincoln's antislavery strategies.

Lincoln adopted the antislavery view that the Constitution made freedom the rule in the United States, slavery the exception. Where federal power prevailed, so did freedom. Where state power prevailed, that state determined the status of slavery, and the federal government could not interfere. It would take state action to achieve the final abolition of American slavery. With this understanding, Lincoln and his antislavery allies used every tool available to undermine the institution. Wherever the Constitution empowered direct federal action, they intervened. As a congressman in 1849 Lincoln sponsored a bill to abolish slavery in Washington, DC. He reentered politics in 1854 to oppose what he considered the unconstitutional opening of the territories to slavery by the Kansas-Nebraska Act.

President Lincoln took full advantage of the antislavery options opened by the Civil War. The Emancipation Proclamation, a military order of the president, undermined slavery across the South. It led to abolition by six slave states, which then joined the coalition to affect what Lincoln called the "King's cure": state ratification of the constitutional amendment that in 1865 finally abolished slavery.