The Constitution of the United States, extolled for 200 years as a child of Enlightenment philosophy, was equally the result of several old-fashioned, unadulterated, unabashed ultimatums, by which one state in the union said to the others: Give us what we want or we go home.

The most famous of these came from the small states, demanding an equal voice in the government, and gave America the "Great Compromise" of July 1787 and the U.S. Senate.

The most infamous came from the states of the Deep South 200 years ago this week, and gave the country the first clause of Article I, Section 9, of the Constitution, the provision barring the new government from interfering with the slave trade.

That provision, and the way it came about, can still make the blood boil two centuries later, as Supreme Court Justice Thurgood Marshall recently demonstrated in his angry speech citing the clause as grounds for suggesting that "we may not all participate in the festivities {of the bicentennial of the Constitutional Convention} with flag-waving fervor."

The debate on the slavery clause began Aug. 21, 1787, when John Rutledge of South Carolina bluntly informed the convention that if it did not provide the South with protection for the slave traffic, the southern states "would not be parties to the union."

It peaked with a chilling prophecy by George Mason, who probably owned more slaves than anyone in the room, that a "national calamity" lay ahead for America because of slavery. "As nations cannot be rewarded or punished in the next world," declared the Virginian, "they must be in this."

And it ended with a notorious bargain -- brokered by Gouverneur Morris of Pennsylvania and consummated on Aug. 29, 1787 -- that made northerners, as well as southerners, collaborators in the cause of slavery.

The story of the slavery clause actually begins with a warning delivered by Charles Cotesworth Pinckney of South Carolina on July 23, 1787, just before the five-member Committee of Detail detached itself from the convention to begin writing the first draft of the Constitution.

Pinckney was a member of one of the most prominent political families of 18th-century America (he, his cousins and his brothers were all active in the independence movement, the war effort and postwar government and politics.) The clan's remarkable matriarch, Eliza Lucas Pinckney, is famous for bringing indigo cultivation to South Carolina.

Charles Pinckney was unusually well-traveled and well-educated for his time, having studied law in England under the great Sir William Blackstone and botany and military science in Europe under some of the continent's most renowned teachers.

The family mansion -- with its gleaming white columns and carved "processions of shepherds, shepherdesses and cupids . . . " -- loomed over Charleston harbor, as if to remind all who arrived in port of the family's importance.

The Pinckney family was particularly hard hit by the war. The British used the mansion as a headquarters when they occupied Charleston, ravaging it and the city. Pinckney, a brigadier general, was taken prisoner along with his cousin, and then lost a son to smallpox and his wife to tuberculosis, leaving him alone with three daughters. Brother Thomas Pinckney was seriously wounded, and the father, Charles the elder, was disgraced by cooperating with the British occupiers of Charleston.

The Pinckneys' trauma mirrored that of South Carolina's ruling classes generally. In addition to the dislocation of the occupation, the traditional power structure of the state had begun to crumble, with upcountry farmers challenging the Charleston "oligarchy" (the Pinckneys, the Rutledges, the Middletons, the Brewtons and others) that had ruled the state for generations. It was only a matter of time, many believed, before the new men would take control.

By 1787 and the Constitutional Convention, South Carolina's once-insular establishment was ready and willing to see a shift of power toward a national government, one that might help open up new markets for its crops, provide stronger defenses from future invasions, and new security from the "leveling spirit" sweeping across their state.

But South Carolina's leadership also knew there was a risk. All 13 states had had slaves at one time or another, but by 1787, only those south of Pennsylvania had them in significant numbers, being roughly one-third slave and two-thirds free.

Among the slave states, however, South Carolina (with 140,000 citizens, 100,000 slaves) had the greatest need for a continuation of the slave trade, in part because of its labor-intensive rice fields. In fact, some said that without slaves, the state would become a large swamp.

The slave traffic was safe as long as the state retained complete sovereignty. But under a national government as proposed in the Constitutional Convention -- with the power to pass laws superior to the laws and constitutions of the states -- the slave trade would be in jeopardy.

For one thing, many Americans, though not abolitionists, found the slave trade morally repulsive or at least embarrassing, especially in the face of the Declaration of Independence, which had said all men were created equal. Also, because of rumblings of insurrection among slaves in the islands of the Caribbean, Americans lived in increasing fear of slave rebellions on their own soil. Already hard-pressed to raise revenue, northerners had no desire to raise their taxes in order to finance armies to protect white southerners.

South Carolina's delegates to the convention -- all Charlestonians, all related to each other, all pillars of the tightly knit leadership circle of that city -- knew they could not go home and present their constituents with a Constitution that did not guarantee continuation of the slave traffic.

Pinckney warned the convention on July 23 that if it failed to insert "some security to the southern states" with regard to slavery, he would be "bound by duty to his state to vote against" the Constitution.

The Committee of Detail, which included South Carolinian Rutledge, heeded Pinckney's words, and in the draft constitution it presented to the convention on Aug. 6, inserted a provision barring the Congress both from prohibiting the slave trade and from taxing it.

"No tax or duty shall be laid . . . on the migration or importation of such persons as the several states shall think proper to admit; nor shall such migration or importation be prohibited," said the provision.

In essence, the clause declared the entire subject of slavery to be the exclusive province of each state, immune from interference by the new federal government.

The South Carolinians and the Georgians then formed a united front to defend the clause from the attack they knew would come. Their strategy was to avoid a debate on the morality of slavery -- which they knew they could not win -- and attempt to convince the others that the continuation of the slave trade was in everyone's interest and that failure to approve the clause would exclude the South from the union.

"Religion and humanity," Rutledge declared as the debate opened on Aug. 21, have "nothing to do with this question. Interest alone is the governing principle with nations. The true question at present is whether the southern states shall or shall not be parties to the union." NEXT MONDAY: The debate and the bargain