"On the eve of the [Amerina] Civil War, returns to capital on southern plantations were greater than in northern factories. American slavery was growing rapidly, and it was the only large system of forced labor in modern history that expanded at a high rate by natural increase. By 1860, four million human chattels were the personal property of four hundred thousand masters and mistresses in the southern states. Many of the master class, and others who hoped to join them, were ready to fight and die for this 'peculiar institution', wich they defended in the name of southern honor, states'rights, and liberty to keep a slave.
At the same time, that slavery was flourishing in the southern states, Americans in the northern states created the world's largest and most dynamic antislavery movement. In 1860, nearly two million people in the northern and western states voted for candidates who condemned slavery and demanded an immediate end to its expansion. Many were deeply offended by the moral wrong of slavery. Some were ready to lay down their lives in the cause of abolation.
In 1861, these two great American forces, slavery and antislavery, met in a violent collision that shook the republic to its foundation. The result was the bloodiest war in American history, and someting else that Abraham Lincoln called a new birth of freedom."
David Hackett Fischer in Liberty and Freedom - A Visual History of America's Founding Ideas (Oxford University Press, 2015)