Too bad you can't go back into time and tell the secessionists that they got it wrong, when they explained in considerable detail why exactly they (thought they) were seceding.
Georgia:
For the last ten years we have had numerous and serious causes of complaint against our non-slave-holding confederate States with reference to the subject of African slavery.... While the subordination and the political and social inequality of the African race was fully conceded by all, it was plainly apparent that slavery would soon disappear from what are now the non-slave-holding States of the original thirteen.
Mississippi
Our position is thoroughly identified with the institution of slavery-- the greatest material interest of the world.
South Carolina:
an increasing hostility on the part of the non-slaveholding States to the institution of slavery, has led to a disregard of their obligations, and the laws of the General Government have ceased to effect the objects of the Constitution. The States of Maine, New Hampshire, Vermont, Massachusetts, Connecticut, Rhode Island, New York, Pennsylvania, Illinois, Indiana, Michigan, Wisconsin and Iowa, have enacted laws which either nullify the Acts of Congress or render useless any attempt to execute them. In many of these States the fugitive is discharged from service or labor claimed, and in none of them has the State Government complied with the stipulation made in the Constitution.
Texas:
She was received as a commonwealth holding, maintaining and protecting the institution known as negro slavery-- the servitude of the African to the white race within her limits-- a relation that had existed from the first settlement of her wilderness by the white race, and which her people intended should exist in all future time.... They demand the abolition of negro slavery throughout the confederacy, the recognition of political equality between the white and negro races, and avow their determination to press on their crusade against us, so long as a negro slave remains in these States.