Congresswoman and presidential candidate Michele Bachmann created a stir recently by insisting on television that America’s Founding Fathers “worked day and night” to abolish slavery. When asked to identify one of them and say what he did on behalf of this noble cause, the only name she produced was John Quincy Adams. He was all of 9 years old when his father, John Adams, persuaded the Continental Congress to vote for independence in 1776.

Ms. Bachmann’s historical gaffe notwithstanding, there is surely a legitimate question here: Was slavery a day and night preoccupation of America’s top leaders during the founding era—1775 to 1800? Dismaying as it may be to many admirers of our revolutionary past, the correct response is: no.

Survival was the issue that preoccupied the Founders and their followers during the eight-year struggle against imperial Britain’s mighty fleet and army. When victory dawned in the 1780s, a new worry became paramount. Gen. George Washington summed it up in a terse sentence in a letter to another Virginian: “I see one head gradually turning into thirteen.”

The divisions and quarrels between the 13 former colonies were making the future of the new nation a very dubious proposition. The cost of the Revolutionary War had reduced the Continental Congress under the Articles of Confederation to an often derisive joke. Without the power to tax, its paper money deteriorated into worthlessness. A bankrupt Congress could not persuade, much less coerce, any state to do anything it regarded as not in its best interest.

At the same time, the Founding Fathers well recognized the serious problem of slavery. George Washington ignored protests from some Southerners and accepted both free and enslaved blacks in his army. In the final years of the war, one in every seven soldiers in his ranks was black. This experience, and his discussions with the idealistic young French volunteer, the Marquis de Lafayette, convinced Washington that slavery was incompatible with American liberty. “There is not a man living,” he wrote to a friend in 1786, “who wishes more sincerely than I do to see a plan adopted for [its] gradual abolition.”

In his first draft of the Declaration of Independence, Thomas Jefferson wrote a scathing condemnation of the slave trade, which he blamed on British greed and hypocrisy. It was edited out of the final version because Southerners wanted the trade to continue. They were supported by New Englanders, whose ships found the human traffic hugely profitable. But Jefferson’s blazing words remained a powerful memory in the minds of many congressmen. “It is written in the book of fate that these people shall be free,” he declared.

John Adams never owned a slave. When he wrote the constitution of Massachusetts in 1779, he asserted as its basic principle: “All men are born free and equal.” In 1781, a Bay State slave named Quok Walker sued for his freedom based on this clause. Walker won and slavery was on its way to oblivion in Massachusetts. Other New England states, and Pennsylvania, began programs for gradual manumission that freed all children born of slave parents. Alexander Hamilton supported a similar program in the New York Manumission Society. So did his partner, close friend and future chief justice of the Supreme Court, John Jay.

But the barely breathing American union remained the Founders’ primary concern. As the 1780s wore on, its international credit at a low ebb, the nation was mired in a deep economic depression. In 1787, George Washington agreed to serve as chairman of a convention that met in Philadelphia to write a new constitution.

Starting from a plan drafted by James Madison, the delegates achieved a political miracle—a document that gave the federal government the power to tax at home and speak for the nation abroad while reserving important rights and responsibilities to the states.

Then, with success seemingly assured, the delegates plunged into an ugly brawl over slavery.

George Mason, a friend and neighbor of Washington, declared the institution brought “the judgment of heaven” on a nation and demanded an immediate end to the slave trade. Northerners furiously criticized a Southern proposal to count a state’s slaves as part of its population—a proposal that would increase the power of the Southern states in Congress (and hence make it more difficult ever to abolish their peculiar institution).

In response, John Rutledge of South Carolina, while admitting that slavery might offend “religion and humanity,” declared that the Carolinas and Georgia could not survive without it. The issue, he said with cold precision, was “whether the Southern states shall or shall not be parties to the Union.”

The delegates convened a special committee to find a solution to this ultimate challenge. The committee proposed permitting the slave trade until 1808, and counting three-fifths of a state’s slaves as a basis for the number of its representatives in Congress. In an emotional speech, 81-year-old Benjamin Franklin persuaded all but three of the delegates to “doubt a little of their infallibility” and accept these and other compromises that made the Constitution a reality.

That same year, Franklin accepted the presidency of the Pennsylvania Society for the Abolition of Slavery. In 1790, he presented a petition to the first federal Congress, urging it to pass a law banning slavery. When George Washington died in 1799, his will set free all of Mount Vernon’s slaves upon the death of his wife, Martha.

Alas, in the new century, unforeseen forces and influences arose that made slavery so immensely profitable for Southern plantation owners that it became entrenched in their way of life. Meanwhile, the rest of the nation became more and more hostile to tolerating slavery on American soil.

And yes, one of the leaders in this mounting assault was John Quincy Adams. The ultimate result was a horrendous civil war—the conflict that the Founders had tried so hard to prevent. It began as a struggle to preserve the indissoluble union they had created. It ended in a triumph for the America they had envisioned and encouraged in their words and deeds—a nation in which freedom belonged to men and women of every race and color.

Mr. Fleming, author of “Liberty! The American Revolution” (Viking, 1997), among many other books, is a past president of the Society of American Historians.