How the Civil War became a war against slavery

It didn’t begin as one.

To be sure, Southern states began seceding from the Union, formed the Confederacy, and fired on Fort Sumter because they feared the new president, Abraham Lincoln, would abolish slavery.

But Lincoln went to war in 1861 to stop the Southern states from seceding and preserve the Union. He insisted that he did not intend to abolish slavery through presidential power. When several Union generals attempted to free slaves in their areas of command, Lincoln stopped them.

Abolitionists were outraged. To them, the war was the ultimate opportunity to destroy slavery. Though slavery was protected by state laws and the Constitution, a war against the Southern rebellion made it fair game in their view under the war powers granted to the president by the Constitution. How could Lincoln, the first president of the antislavery Republican Party, not seize this opportunity?

Lincoln wanted to end slavery, but he had to wait for the right time. Most of his own party didn’t want to see slavery abolished, only stopped from expanding father into the West. Northern Democrats had no quarrel with slavery. Four slave states, the Border States, had not seceded from the Union. And Lincoln believed that many within the 11 Rebel states still harbored Unionist sympathies. If he abolished slavery in 1861, he expected to lose support for the war in the North, push the Border States to secede, and harden the whole South against the Union. In short, by attempting to abolish slavery, he would lose the Union and with it the possibility of ever abolishing slavery in an independent Confederacy.

But defeating the Rebels militarily wasn’t as easy the president hoped it would be. The Union suffered a disastrous defeat in the first major battle of the war, Bull Run, in July 1861. Eight months later, Union Major General George B. McClellan led his Army of the Potomac up the Virginia Peninsula to attack the Confederate capital at Richmond. McClellan’s Peninsula Campaign remains the largest ever waged in North America. By late May 1862, McClellan was closing in on Richmond, and an end to the war seemed within sight — an end that would have left slavery intact.

At this stage, the commander of the Confederate army facing McClellan fell wounded in battle and was replaced by General Robert E. Lee. Though widely regarded as one of the country’s leading military minds, Lee had never commanded an army in battle. He called on Confederate forces under Major General Thomas “Stonewall” Jackson to help attack and defeat McClellan in a battle that Lee hoped would win Confederate independence.

The armies fought a ferocious series of engagements outside Richmond from June 25 to July 1. Though little known today, the Seven Days was the largest battle of the Civil War and presented Lee with his best chance for a decisive victory as McClellan retreated from Richmond and exposed his army to destruction. The Confederates squandered their opportunity but thwarted McClellan’s campaign.

Disastrous as the defeat on the Peninsula was, Lincoln decided that the moment was ripe to change course on the slavery question. The South had demonstrated that its allegiance was not to be gained by preserving slavery, and the North would see an attack on slavery as a military expedient without which the war could not be won. Lincoln drafted the Emancipation Proclamation that July. It did not abolish slavery wholesale, as Lincoln had to keep the Border States from seceding and could not exceed his presidential war powers without fear of backlash from a pro-slavery Supreme Court. The proclamation freed slaves in Rebel territory.

Lincoln announced it to the public on September 22, 1862 following the Union victory at Antietam. He signed it into law on January 1, 1863, at which point the Civil War truly became a war against slavery. Slavery was finally abolished in the United States by the 13th Amendment to the Constitution, passed by Congress and ratified by the states in 1865.

Learn more about the Seven Days, the Civil War’s forgotten turning point.