THE SECTIONAL controversy that issued in the Civil War involved not only the morality of slavery but also and more fundamentally the nature of American political and social institutions. In comparative perspective American society was liberal and democratic from its very inception. Nevertheless it tolerated if it did not positively encourage an institution that, irrespective of the intentions of particular individuals, stood as a continual reproach to and contradiction of the democratic values that a growing portion of the American people regarded as the very basis of American nationality. The ability of slaves to carve out spheres of personal autonomy notwithstanding, slavery denied the right of four million black persons to the most elementary kind of self-determination. It literally denied the right of self-government that was the touchstone of the American polity. By 1861 moreover efforts to protect and promote slavery threatened the very integrity of the federal republic, eventually provoking northerners to fight in its defense. Once war began, the desire to preserve the Union merged with hostility toward slavery as the antithesis of republican institutions to produce the decision for emancipation. Amidst the profound social upheaval that the abolition of slavery caused, a combination of principled and expedient considerations led the Union Congress to pass a series of civil rights laws and constitutional amendments—the first in United States history—that insisted on national application of the principle of equality before the law in each state irrespective of race.
The principle of equal rights was a cardinal feature of the republican ideology that had sustained the American people in their revolutionary origins and guided them as they expanded