The Emancipation Proclamation stands as the single most important accomplishment of Lincoln’s presidency. The preliminary proclamation, announced on September 22, 1862, served as a warning for Southern states that if they did not abandon the war, they would lose their slaves. More important, it was the first step toward the official abolition of slavery in the United States. While many Northerners were not initially abolitionists, their support of Abraham Lincoln and the Union military, as well as the demonstrated determination of slaves to...