In 1789, Ben Franklin referred to the "peculiar institution" as it was sometimes called as "an atrocious debasement of human nature. . . ." However, the beginnings of the abolitionist movement would not really take root until the 1830's as a catalyst for increasing animosity and hostility between slaveowning states (by then, just the Southern and border states and the Northern states.
The failure of the Articles of Confederation had created what many considered to be a grave situation, wondering if the country that had lost so much in its fight for independence could actually survive as a nation, and the need for a central government was great. Therefore, although the issue reared its ugly head from time to time during the convention, it was usually glossed over without too much protest, especially as the document came closer to being finished, because no one expected it to be ratified if great compromises weren't made.
The Convention had representatives from every corner of the United States, including, of course, the South, where slavery was most pronounced. Slavery, in fact, was the backbone of the primary industry of the South, and it was accepted as a given that agriculture in the South without slave labor was not possible. . . .The cultivation of rice, cotton, and tobacco required slaves to work the fields from dawn to dusk. If the nation did not guarantee the continuation of slavery to the South, it was questioned whether they would form their own nation.
In America's Constitution, Akhil Reed Amar writes of the Constitution and slavery, "Slavery was the original sin in the New World garden, and the Constitution did more to feed the serpent than to crush it." By the mid-1800's the compromises and willingness to ignore something that needed to be addressed as the issue that reared its head at the Constitutional Convention became the focus of a nation at war with itself leading to the Civil War.