The Antislavery Movement Moral and demographic pressures strained the compromises on slavery brokered in 1789. The rise of abolitionism in the North intensified the sectional divide in the nation, while the growth of the black population in the South made the prospect of emancipation all the more threatening to entrenched white interests. Organizations such as the American Anti-Slavery Society and individuals such as Frederick Douglass popularized the evils of slavery and pressed northern states for reform. In the South, leaders such as James Henry Hammond defended slavery as a just and natural institution without which civil society could not be preserved. “[A]ny species of emancipation with us would be followed instantly by civil war between the whites and blacks,” he remarked in 1836, “A bloody exterminating war, the result of which could not be doubtful, although it would be accompanied with horrors such as history has not recorded.”

The “Gag Rule” Because the nation was so deeply divided on slavery, national leaders attempted to keep it out of federal politics. The “Gag Rule” adopted by the House of Representatives required that all petitions relating to slavery be tabled without discussion. Antislavery politicians argued that the slave interests had effectively nullified the First Amendment by barring discussion of the issue on the national level. However, the westward expansion of the United States made it all but impossible to keep slavery off the national agenda.

Manifest Destiny and the Mexican War In an 1845 article on the annexation of Texas, John L. O’Sullivan wrote that it was the nation’s “manifest destiny to overspread the continent allotted by Providence for the free development of our yearly multiplying millions.” The idea became an article of faith in American politics as the nation expanded westward. But Mexican territory stood between the United States and the fulfillment of its manifest destiny to reach the Pacific. Most of this territory was vulnerable to seizure, as it was sparsely populated. Texas was the first state to be settled at the expense of Mexico. Annexing Texas, a slave territory, became a controversial issue because it would have broken the fragile balance between slave and free states. In 1845, Congress passed a joint resolution bringing Texas into the Union. This provoked a crisis with Mexico, which refused to recognize U.S. sovereignty over the state. President Polk sent a delegation to Mexico, ostensibly to resolve the dispute over Texas but actually to negotiate the purchase of New Mexico and California, which made up half the territory of the nation. When Mexico refused, Polk ordered U.S. forces to take up positions along the Rio Grande. The move provoked Mexico to cross the Rio Grande, triggering war.

The Wilmot Proviso The Mexican War further complicated the national debate on slavery. When President Polk asked Congress for an appropriation to pay for the war, David Wilmot, an antislavery Democrat from Pennsylvania, added a rider stipulating that “neither slavery nor involuntary servitude should ever exist in any part of the territory.” The proviso was repeatedly rejected by the Senate, but passed the House of Representatives every time, further exacerbating the divide between North and South. It also prompted a sea change in the national debate over slavery. Southern leaders such as Jefferson Davis and John C. Calhoun now argued that Congress had no authority to enact prohibitions in the national territories that discriminated against citizens of the slave states. Slaves were property like all other property, they argued, and the Constitution unambiguously protected property in the territories. Whereas the status of slavery in the territories had before been susceptible to negotiation and compromise, it now was a matter of constitutional rights.

Compromise of 1850 As controversy threatened to disrupt the Union, Senator Henry Clay stepped forward to broker a compromise. By now an elder statesman, his incomparable political skills pulled the nation back from the brink. He presented a series of resolutions to the Senate on February 5–6, 1850: California would be admitted to the Union as a free state, and the rest of the territory taken from Mexico would be organized without any restrictions on slavery. The settlers themselves would decide the status of slavery under what would come to be called “popular sovereignty.” In addition, slavery would be prohibited in the District of Columbia, and a strong fugitive slave law would be passed compelling the northern states to return runaway slaves to their owners. The proposal was vigorously debated. John C. Calhoun opposed it on constitutional grounds, suggesting instead a constitutional amendment that would give the sections a veto in national legislation. An amendment would settle once and for all the persistent struggle over the status of slavery in the nation. Daniel Webster threw his support behind the compromise, ensuring with his stature that northern congressmen would follow suit. However, he also alienated abolitionists who believed that the compromise was a deal with the devil. Whig Senator William Seward expressed this view, charging that the compromise was “radically wrong and essentially vicious.”

Fugitive Slave Law In Prigg v. Pennsylvania (1842), the Supreme Court held that the federal government had exclusive jurisdiction over the return of fugitive slaves across state lines. Justice Story ruled that the Fugitive Slave Law of 1793 was the only governing law on the matter. But because the federal government had exclusive jurisdiction to prescribe the rules governing the return of fugitive slaves, it also had exclusive jurisdiction to enforce that law. Thus states were in no way obligated to assist in the return of runaway slaves. The Fugitive Slave Law, part of the Compromise of 1850, established a process for the return of escaped slaves in which it was all but impossible for alleged runaways to prove their free status. In order to secure the return of alleged fugitives, owners had to present an affidavit of ownership to a federal judge or commissioner. The act further stipulated, “In no trial or hearing under this act shall the testimony of such alleged fugitive be admitted in evidence; and the certificates . . . mentioned shall be conclusive of the right of the person or persons in whose favor granted to remove such fugitive to the State or Territory from which he escaped.” Those who rendered assistance to runaway slaves were subjected to civil and criminal penalties. The act only served to exacerbate the controversy over slavery. Abolitionists boldly defied the law by openly aiding runaways. They popularized its injustice to generate support for their cause. The poet Henry Wadsworth Longfellow wrote of the law, “What a disgrace this is to a republic of the nineteenth century.”

Kansas-Nebraska Act The Kansas-Nebraska Act removed the last barrier to the expansion of slavery in the territories. The product of a political bargain struck by Senator Stephen Douglas, the act repealed the Missouri Compromise of 1820 in exchange for southern support for a northern route for the transcontinental railroad. Under the Kansas-Nebraska Act, the land west of the Mississippi was divided into the territories of Kansas and Nebraska. There, the settlers would decide the legal status of slavery by popular sovereignty.

The Supreme Court and the Slave Trade Before the Supreme Court took up the issue of slavery as a domestic institution, it considered the status of the slave trade under international law. United States v. The Schooner Amistad involved a mutiny by African slaves aboard a Spanish slave ship originating in Cuba. The ship was intercepted off the coast of Long Island and taken to Connecticut. When the slaves were charged with murder and piracy, local abolitionists rallied around them, publicizing the case and providing legal counsel. Under a bilateral treaty, the United States was required to return to Spain any ships and merchandise seized on the high seas by pirates or robbers. But Justice Story ruled that the treaty was inapplicable here: the Amistad Africans were not merchandise because the slave trade was illegal under U.S. and Spanish law. “They are natives of Africa,” he wrote, “and were kidnapped there, and were unlawfully transported to Cuba, in violation of the laws and treaties of Spain, and the most solemn edicts and declarations of that government. By those laws, and treaties, and edicts, the African slave trade is utterly abolished; the dealing in that trade is deemed a heinous crime; and the negroes thereby introduced into the dominions of Spain, are declared to be free.”

Slavery and State Police Powers Groves v. Slaughter (1841) turned on the enforceability of loans for the purchase of slaves in Mississippi. A provision of the state constitution prohibited the interstate purchase of slaves by Mississippi residents. Debtors argued that the illegality of the transactions made the loans unenforceable. The majority upheld the loans on narrow grounds, but Justice McLean dissented, going further than the issue required. He called slavery an evil and held that the right of states to exclude slaves was “higher and deeper than the Constitution.” This prompted the other justices to speak out in separate opinions as well, bringing the cacophonous national debate on slavery into the Supreme Court.

The Dred Scott Case At the heart of the case was the status of Dred Scott, a Missouri slave whose owner brought him to Illinois, a free territory. Scott claimed that his residence in Missouri gave him standing to bring suit in the federal courts and rendered him a free man. The precedent of Strader v. Graham (1851) supported Scott’s argument, and the Court could have narrowly disposed of the case had public pressure not moved the justices to rule on the broader issue of whether the Constitution allowed Congress to prohibit slavery in the territories. Taney wrote the majority opinion, which found that Scott was not a citizen of Missouri. Although he could have ended the matter there, the chief justice went further, finding that the Missouri Compromise was unconstitutional because the Fifth Amendment protected property in slaves. The decision removed any reason for political compromise on the part of South, setting the stage for the fratricidal conflict of the Civil War.

Ableman v. Booth (1859) In Ableman v. Booth, the Supreme Court held that a Wisconsin court could not order the release of a person imprisoned under the authority of the United States. That the prisoner in question happened to stand accused of assisting a runaway slave in violation of the Fugitive Slave Act only underscored the impression on the part of many northerners that slave interests dominated the Court, and that it was too deeply biased to render impartial justice.

Lincoln–Douglas Debates The Lincoln–Douglas Debates introduced Abraham Lincoln to a national audience. The series of seven debates over the course of 1858 were part of the candidates’ campaigns for one of Illinois’s two Senate seats. Although Douglas won the election, the debates put Lincoln on the national political map and helped to define him as a candidate for the presidency in 1860.

John Brown On October 16, 1859, a group of abolitionists led by John Brown raided the Virginia town of Harpers Ferry, seizing the federal arsenal there in the hopes of provoking a slave revolt. The culprits were captured and tried, and Brown was sentenced to death for treason. The event served to exacerbate political tensions. When Congress met in December that year, Senator James Hammond commented, “Every man in both Houses is armed with a revolver-some with two and with a bowie knife.”

Election of 1860 Never has the outcome of an election been more consequential than it was in 1860. The contest between the Democratic candidate, Stephen Douglas, and the Republican candidate, Abraham Lincoln, would determine whether the nation went to war. Douglas had enough national support to hold the country together, but Lincoln’s support rested almost exclusively in the North and West. Lincoln’s victory signaled to many in the South that secession and war were the only way forward.

Secession and Disunion South Carolina led the way to the rupture of the Union. In the wake of Lincoln’s election, the state summoned a convention that adopted an ordinance of secession on December 20, 1860. Senator John Crittenden made a last-ditch effort to spare the nation from war by proposing an unamendable constitutional amendment restoring the Missouri Compromise. Lincoln urged Republicans to reject the Crittenden Amendment, prompting the secession of six more states. By now, war was inevitable.