The American Civil War is best remembered as the conflict that freed the slaves, but the abolition of slavery wasn’t even among the original aims of the northern war effort. Abolition had been widely advocated in the North for decades, but it was far from universally embraced at the outbreak of hostilities in 1861. There were indeed four slaveholding states that remained in the Union—Delaware, Maryland, Kentucky, and Missouri—and President Abraham Lincoln, aware of their strategic “border” location and wary of tipping their fragile loyalty toward the Confederacy, was careful not to antagonize them by suggesting that abolition was even an incidental goal of the Northern cause.
Throughout the first two years of a conflict far bloodier than anyone had anticipated, Lincoln repeatedly articulated what he felt that cause to be: the preservation of the Union. The existential threat to the United States represented by the South’s secession was to him his sole mandate to wage such a costly war. This was not merely a politically expedient public posture, but his own personal conviction: as he wrote privately to Horace Greeley in 1862
My paramount object in this struggle is to save the Union, and is not either to save or to destroy slavery. If I could save the Union without freeing any slave I would do it, and if I could save it by freeing all the slaves I would do it; and if I could save it by freeing some and leaving others alone I would also do that.
Lincoln’s own personal views on slavery are difficult to determine and have been much debated. His comments and observations on the subject are often confusingly contradictory, reflecting an ambivalence about race common even among the most “enlightened” individuals of the day. There is, however, much evidence to suggest that Lincoln’s perspective on slavery evolved over time, and certainly by late 1862 he had come to see in the abolition of slavery a higher cause through which the war’s unprecedented slaughter might be redeemed.
In 1863, Lincoln issued the Emancipation Proclamation, freeing the slaves of the Confederacy. Although this grand gesture actually did nothing for slaves within the Union itself, it did help give a renewed sense of purpose to the war-weary North. Later that same year, while consecrating the site of the war’s bloodiest battle, Lincoln gave his most eloquent expression of this new, higher meaning. The Gettysburg Address affirmed for all—and for all time—that the Civil War was no longer merely a struggle to preserve a political union; it was now a moral crusade.