During this time many Americans found it easy to reconcile slavery with the Bible, but a growing number rejected this defense of slavery. A small antislavery movement, led by the Quakers, appeared in the 1780s, and by the late 1780s all of the states had banned the international slave trade. No serious national political movement against slavery developed, largely due to the overriding concern over achieving national unity. When the Constitutional Convention met, slavery was the one issue "that left the least possibility of compromise, the one that would most pit morality against pragmatism." In the end, many would take comfort in the fact that the word "slavery" never occurs in the Constitution. The three-fifths clause was a compromise between those (in the North) who wanted no slaves counted, and those (in the South) who wanted all the slaves counted. The Constitution (Article IV, section 4) also allowed the federal government to suppress domestic violence, a provision that could be used against slave revolts. Congress could not ban the importation of slaves for 20 years. The need for the approval of three-fourths of the states for amendments made the constitutional abolition of slavery virtually impossible.