Fast-forward 30 years to the Civil War, the greatest constitutional crisis in American history. It was the only time in which the United States resolved a constitutional issue (slavery) not by force of argument but by force of arms. Immediately after the defeat of the slaveholding Confederacy, three new amendments were ratified which fundamentally changed the Constitution: the 13th, 14th and 15th Amendments, commonly called the Reconstruction Amendments.
The 13th Amendment (1865) prohibited slavery throughout the United States; the 14th Amendment (1868) mandated certain standards of fairness and equality in how those former slaves could be treated; and the 15th Amendment (1870) sought to guarantee the voting rights of former slaves—at least former male slaves. These changes were so fundamental that some scholars consider the Reconstruction Amendments to have created a second American Constitution.
The Constitution of 1787 contained very few limitations on the powers of state governments, and the Bill of Rights had not added any more to that list. The 13th, 14th and 15th Amendments, however, were intended to place some serious restrictions on what the states could do.