“The Civil War began over a simple question,” writes historian Sean Wilentz in a recent New York Times op ed that drew controversy: “Did the Constitution of the United States recognize slavery—property in humans—in national law?” So it may seem to Wilentz and to like-minded historians such as James Oakes and James Huston. But anyone alive at the time would likely have provided a different answer to Wilentz’s “simple question.”

Two key points are at stake here. Wilentz first asserts that the Constitution was fundamentally antislavery. He thereby stirred a lively controversy. His critics, notably David Waldstreicher, contend that the Constitution’s framers in Philadelphia in 1787 knew they had to mollify slaveholders. They omitted the word “slave” from the final document to shield national hypocrisy and embarrassment, but they crafted numerous safeguards for slavery. “On balance,” Waldstreicher concludes, “the Constitution was deliberately ambiguous—but operationally proslavery.” He downplays as “damage control” James Madison’s famous comment, that he “thought it wrong to admit in the Constitution the idea that there could be property in men.”

This essay addresses Wilentz’s second key assertion, that North-South disagreements about the Constitution were the rock that split the Union in 1860-61. The South insisted that “property in humans” enjoyed national sanction, Wilentz argues, but the North denied the South’s claims and went to war to defend an antislavery interpretation of the Constitution. The evidence shows, instead, that other matters took priority. Divergent Northern and Southern understandings of the Constitution did not start the war.

Abraham Lincoln and other antislavery Northerners did indeed believe that the Southern-dominated Supreme Court had twisted the Constitution to open the territories to slavery and to make it potentially legal in the free states. He and his fellow Republicans complained that the court’s Dred Scott decision undermined the antislavery aspirations of the Founding Fathers and threatened to make slavery a national institution.

White Southerners countered to insist that the Court had correctly validated their right to hold slave property in the territories. If Republicans ignored Dred Scott and kept trying to bar slavery from the territories, it showed that they were reckless extremists who stood ready to trample the Constitution. It showed too that they might endanger slavery in the slave states.

Lincoln denied that he or the Republican Party would tamper with slavery where it already existed by state law, but he rejected the Supreme Court’s view that the right to hold slave property was “distinctly and expressly affirmed in the Constitution.” The idea that “there could be property in man” had been deliberately excluded from the Constitution, Lincoln stated. The Founding Fathers had used “covert language” rather than refer directly to slavery.

However divisive these constitutional disagreements, they did not send men into battle. A struggle for political power, together with popular fears roused by overheated political rhetoric, stood at the center of the North-South dispute and fueled the polarization that sparked the war.

Antislavery Northerners believed the South wielded too much power in the Union. The Republican Party coalesced in the 1850s to roll back the “Slave Power” and prevent it from seizing western territories. Republicans campaigned to evict the Southern-dominated Democratic Party from its stranglehold on national office. They vowed to enable the free white men of the North to gain the political muscle to which their numbers entitled them.

Proslavery Southerners saw the Republican Party as a deadly menace, which first would deny them access to the territories and then attack slavery in the states where it existed. Georgia’s Howell Cobb, who knew better, warned that Republicans were committed to “immediate and unconditional abolition in every State” and that Lincoln planned to build up a party in the South to promote “this insidious warfare upon our family firesides and altars.” Misled by the wild exaggerations of leaders such as Cobb, many ordinary white Southerners suspected the worst.

Lincoln tried to quiet the white South’s hysteria. He knew that Southern alarmists charged repeatedly that Republicans were abolitionists in disguise who plotted to unleash slave rebels and murder white women and children. He assailed all such grotesque “misrepresentations” and condemned John Brown’s “absurd” raid on Harpers Ferry, Virginia, in October 1859. “John Brown was no Republican,” Lincoln insisted. To suggest otherwise was “simply malicious slander.”

Without doubt, Lincoln viscerally disliked slavery. Thinking about it made him miserable. But he and most other antislavery Northerners also prized a Union with slaveholders and wanted it preserved. He was “committed to values that could not logically be reconciled,” historian David Potter once wrote. Republicans hoped that slavery eventually might disappear. But they carefully restricted their antislavery agenda to the territories. They read the Constitution to mean that they had no power to touch slavery in the states where it existed. They counted upon white Southerners to realize, at some point in the future, that free labor would create greater prosperity and productivity than slave labor.

Some Republicans such as Ohio’s Joshua Giddings saw antislavery as a moral imperative and demanded a more aggressive program to “denationalize” slavery. They wanted to absolve the federal government from any responsibility for upholding or sustaining the system. So they called for action—to abolish slavery in the District of Columbia, to restrict or eliminate the interstate slave trade, to repeal the Fugitive Slave Act, and to prevent additional slave states from entering the Union. Their rallying cry was “freedom national.”

But the stance assumed by the Republican Party in its victorious 1860 campaign gave short shrift to “freedom national” absolutists. Mainstream Republican leaders, led by Lincoln, focused narrowly on the territories and on the long-run hope that white Southerners might reconsider their addiction to forced labor. If Republicans embraced the plan to “denationalize” slavery, Lincoln cautioned, they would lose the North’s swing voters. He warned insiders that demanding repeal of the Fugitive Slave Act would wreck the party. “I confess I hate to see the poor creatures hunted down, and caught, and carried back to their stripes, and unrewarded toils,” he told a friend, “but I bite my lip and keep quiet.”

Republican senator James R. Doolittle of Wisconsin pointed out that his party rejected both the “unfounded” idea that the Constitution “abolishes slavery” and the Southern dogma that the Constitution was “slavery-extending.” Instead, the Constitution must be “neutral.” It “never could have been formed at all,” Doolittle reasoned, on an antislavery or proslavery basis. He urged his Southern colleagues to quit insinuating that Republicans had the same objectives as abolitionists and to “quiet the alarm” among their people.

Lincoln’s supporters and surrogates fanned out across the free states in 1860 to stir a huge turnout—and to reassure potential voters that no harm could result from challenging the Slave Power. Lincoln was well aware of Southern threats to disrupt the Union, but he discounted them. “The people of the South have too much of good sense, and good temper, to attempt the ruin of the government,” he wrote privately—“at least, so I hope and believe.” White Southerners could “do as they please” about slavery in the states where it existed.

The intensifying political crisis came to a head in November 1860 when Lincoln was elected president. His victory ignited a runaway popular panic in the Deep South about the pending perils of “Black Republican” rule. Seven states suddenly seceded from the Union rather than “submit” to Lincoln. He tried to nurture a sober second thought, even going so far as to accept a constitutional amendment to make explicit what he had always regarded as implicit—that Congress could not “abolish or interfere” with slavery in the slave states. His first inaugural address on March 4, 1861, pleaded for peace and beseeched secessionists to retrace their course. But the Deep South paid no heed and decided to fight for its independence.

Secession created an immediate impasse far more pressing than the long-run future of slavery or the technicalities of constitutional interpretation. If the Deep South could break up the Union simply because it had lost an election, Northerners judged, it imperiled what historian Russell McClintock felicitously identified as “America’s unique experiment in self-government, whose example was to have inspired the overthrow of monarchy and the spread of republican principles throughout the world.” Explosive Northern anger was generated far more by the spectacle of secessionists seizing federal property and dishonoring the American flag than by the maltreatment of Southern slaves or by disagreements about the Constitution.

Blind to abundant historical evidence that war had the potential to disrupt slavery, secessionists sleepwalked heedlessly into catastrophe. The Republican Party posed no danger to slavery. But war did. Lincoln’s treasury secretary, Salmon P. Chase, observed retrospectively that white Southerners had fallen victim to collective “insanity.” Had they stayed in the Union, they might have kept slavery “for many years to come.” No party or public feeling in the North “could ever have hoped” to touch it.

James Madison and Abraham Lincoln thought alike. Both considered slavery inconsistent with American ideals and both hoped the paradox of slaveholding in an ostensibly free republic might be peacefully resolved in the distant future. Both whistled in the dark as they awaited protracted and gradual antislavery advances. Lincoln endlessly professed confidence that stopping slavery’s spread to the territories would be the first step toward ultimately ending it. But he had no second step in mind, and he once mused that slavery might last for another century. He did not know that the pernicious system was about to self-destruct and that he would come to be known as “The Great Emancipator.”