Two weeks before Christmas 1829, 60 copies of a book slipped off a ship at the port of Savannah and found their way to a local black preacher. Seeing what was inside, he turned them over to the police at once. They seized every copy.

The author, it turned out, was a free and educated black man named David Walker, a Boston activist and used-clothing dealer.

As its title suggested, the book was an “Appeal” to “The Colored Citizens of the World, but in Particular and Very Expressly to those of the United States of America.” Yet appeal was a tame word for the prophecy smoldering between its covers, clearly directed towards the nation’s enslaved laborers. The police may have flipped to page 28: “It is no more harm for you to kill a man, who is trying to kill you, than it is for you to take a drink of water when thirsty.” Page 35 argued that owners denied slaves education because it would reveal their right to “cut his devlish throat from ear to ear, and well do slave-holders know it.”

Perhaps the police clapped the book shut after page 42, startled when it aimed at whites directly: “Unless you speedily alter your course, you and your Country are gone!!!!!! For God Almighty will tear up the very face of the earth!!!”

Shortly after this seizure, 20 more copies appeared in Georgia’s capital, then another 30 in Virginia. More materialized in New Orleans and Charleston two months later. Before the end of the year, more than 200 had breached the Carolinas. Police scrambled but failed to confiscate most copies, despite in some instances sending undercover agents into black communities. In certain parts of the South, evidence emerged that the book was in fact spreading via networks of runaways. Whites began to panic. Frederick Douglass later reflected that the Appeal “startled the land like a trump of coming judgment.”

Hoping to stanch the book’s flow, state officials called emergency sessions and passed legislation with astounding swiftness. In the words of historian Lacy K. Ford, Jr., “the security furor triggered by the appearance of David Walker’s pamphlet was without precedent.” In Georgia, legislators convened on December 21 and passed new laws before the end of the year. Georgia and North Carolina banned black sailors from entering their ports and outlawed the circulation of questionable literature, punishable by death in the former. Louisiana and Virginia strengthened codes that banned free blacks from entering the state or outlawed literacy instruction for slaves.

The day after the Appeal first appeared in the South, the mayor of Savannah wrote to the mayor of Boston, Harrison Gray Otis, requesting that Mr. Walker be punished for the distribution of his “highly inflammatory work.” Otis conceded that the book was “extremely bad,” but it was not strictly illegal according to any Massachusetts law. He could neither confiscate it nor punish Walker lawfully.

This was more than a failure to harmonize Southern and Northern law; it was a symptom of what Abraham Lincoln would later call a “house divided against itself” on fundamental definitions of property rights versus human rights. The “right to tamper with this species of property belongs to no man, and no body of men, but their owners,” one Georgia journalist wrote in response to the Appeal –  this was “the point of delicacy, and the sanctum sanctorum of Southern feeling.”

Otis did send men to question Walker, perhaps hoping that some pressure from the mayor’s office would unnerve him. To their surprise, Walker not only openly claimed the Appeal as his handiwork, but made plain his intention to circulate more copies at his own expense – also perfectly legal in Massachusetts. Otis could do little besides warn New England ship captains about the book and urge his southern countrymen to remain calm. Otis pointed to “the insignificance of the writer, the extravagance of his sanguinary fanaticism” as evidence that everything would blow over if everyone kept their heads.

But in reality, more than any book in American history, the Appeal forced a choice between peace of mind and owning slaves.

Was Walker, as Otis said, an extravagant fanatic, not worth their panic?

He was born in Wilmington, North Carolina, in 1796. His father, a slave, died before his birth. His mother, free, passed her freedom on to him as the law allowed. Walker nonetheless despised his birthplace, a “bloody land … where I must hear slaves’ chains continually.” He left for the North, and it seems no coincidence that he sent 200 copies of the Appeal to his hometown alone, nearly double the amount that he had sent elsewhere.

Walker plugged into nearly all the major networks of antebellum black activism. He was a leader in AME Church communities in Charleston, Philadelphia, and Boston –  all cities with organized free black communities – and was active in Boston’s Prince Hall Freemasonry, where he also helped found the Massachusetts General Coloured Association. In addition to composing his own antislavery writings and speeches, he was even a sales agent for Freedom’s Journal, America’s first black newspaper. Walker was welcome company among the organized black North.

And if his Appeal was peppered plentifully with prophecy and exclamation marks, its core argument was simple and unnerving. He began with the common premise that slavery defied God’s law because it usurped God’s authority. (“Have we any other Master but Jesus Christ alone?” he posed plainly.) As such, slavery was destined to end either peacefully or violently. Those who defended it, he argued, “forget that God rules in the armies of heaven.”

But even slave owners like Thomas Jefferson had acknowledged as much years earlier. “I tremble for my country when I reflect that God is just,” he famously brooded, wondering if a revolution was coming for America’s slave economy. 

Walker terrified readers by unfolding this premise a step further, from passive apocalypticism to active holy war: if slavery defied God’s law, so did obedient slaves. Rebellious slaves, therefore, were God’s warriors.

“The man who would not fight … in the glorious and heavenly cause of freedom and of God – to be delivered from the most wretched, abject and servile slavery,” he wrote, “ought to be kept … in chains, to be butchered by his cruel enemies.” Echoing the American Revolution, Walker transformed God’s law into battle lines, Providence into a call-to-arms. This combination of militant prophecy and straightforward reasoning was precisely what whites feared would rouse slaves.

The Appeal came in the wake of bloody slave rebellions that had already practiced what Walker preached. Though it came nearly a century earlier, people still told stories about the Stono Rebellion of 1731, while revolts only increased after the revolutions in America, France, and Haiti. The conspiracy of Gabriel “Prosser” in 1800, the German Coast Uprising of 1811, and Denmark Vesey’s conspiracy in 1822 – just seven years before the Appeal – all put muscle behind Walker’s prophecy. When Nat Turner staged the country’s largest and deadliest slave rebellion the year after the Appeal’s initial appearance, many slaveholders found their worst fears confirmed.

Walker’s pamphlet was arguably more terrifying than these rebellions, precisely because it could spread a precise, persuasive message much further and faster than the charismatic leadership that catalyzed these revolts. Two months after Walker sent his 200 copies of the Appeal to North Carolina, for instance, white residents overheard talk of a plot circulating among a broad network of slaves. If former slave rebellions had been scarier instances of real violence, they were also restricted to local phenomena. Walker’s Appeal was the first instance in which revolt haunted the South as a whole. “None of these insurrections,” in the words of Ford, “generated the breadth of alarm” as the circulation of the Appeal, whose call for slaves “to throw off the chains of slavery, struck raw nerves on a broader scale.”

The Appeal even encouraged some efforts to diminish slavery’s presence in the South. Georgia, for instance, introduced a partial ban on the importation of slaves, and its governor pushed for a full ban, while the Appeal re-energized the Colonizationist movement in Mississippi.

After Nat Turner’s rebellion, this brief outburst of antislavery animus faded just as full-throated defenses of slavery arose from apologists like John C. Calhoun and George Fitzhugh. Then Walker died in August 1830, a short year after the Appeal’s appearance. (Some suspected a proslavery assassination plot, but it was likely tuberculosis.)

If Walker failed to scare America straight, his prophecy came true in another sense. He believed that God, as a “just and holy Being,” would “one day appear fully in behalf of the oppressed” – through either the revolt of the oppressed or the self-destruction of the oppressors, “caus[ing] them to rise up one against another.” Had he lived to witness the eruption of the Civil War 30 years later, Walker may have found both prophecies fulfilled.