Humanities › History & Culture Wilmot Proviso Failed Amendment to a Finance Bill Had Major Repercussions Related to Slavery Share Flipboard Email Print Getty Images History & Culture American History Important Historical Figures Basics Key Events U.S. Presidents Native American History American Revolution America Moves Westward The Gilded Age Crimes & Disasters The Most Important Inventions of the Industrial Revolution African American History African History Ancient History and Culture Asian History European History Genealogy Inventions Latin American History Medieval & Renaissance History Military History The 20th Century Women's History View More By Robert McNamara History Expert Robert J. McNamara is a history expert and former magazine journalist. He was Amazon.com's first-ever history editor and has bylines in New York, the Chicago Tribune, and other national outlets. our editorial process Robert McNamara Updated October 24, 2019 The Wilmot Proviso was a brief amendment to a piece of legislation introduced by an obscure member of Congress that set off a firestorm of controversy over the issue of slavery in the late 1840s. The wording inserted into a finance bill in the House of Representatives would have repercussions that helped bring about the Compromise of 1850, the emergence of the short-lived Free Soil Party, and the eventual founding of the Republican Party. The language in the amendment only amounted to a sentence. Yet it would have had profound implications if approved, as it would have prohibited slavery in territories acquired from Mexico following the Mexican War. The amendment was not successful, as it was never approved by the U.S. Senate. However, the debate over the Wilmot Proviso kept the issue of whether slavery could exist in new territories in front of the public for years. It hardened sectional animosities between North and South, and ultimately helped put the country on the road to the Civil War. Origin of the Wilmot Proviso A clash of army patrols along the border in Texas sparked the Mexican War in the spring of 1846. That summer the U.S. Congress was debating a bill that would provide $30,000 to begin negotiations with Mexico and an additional $2 million for the president to use at his discretion to try to find a peaceful solution to the crisis. It was assumed President James K. Polk might be able to use the money to avert the war by simply buying land from Mexico. On August 8, 1846, a freshman congressman from Pennsylvania, David Wilmot, after consulting with other northern congressmen, proposed an amendment to the appropriations bill that would ensure slavery could not exist in any territory which might be acquired from Mexico. The text of the Wilmot Proviso was one sentence of fewer than 75 words: "Provided, That as an express and fundamental condition to the acquisition of any territory from the Republic of Mexico by the United States, by virtue of any treaty which may be negotiated between them, and to the use by the Executive of the moneys herein appropriated, neither Slavery nor involuntary servitude shall ever exist in any part of said Territory, except for crime, whereof the party shall be first duly convicted." The House of Representatives debated the language in the Wilmot Proviso. The amendment passed and was added to the bill. The bill would have gone on to the Senate, but the Senate adjourned before it could be considered. When a new Congress convened, the House again approved the bill. Among those voting for it was Abraham Lincoln, who was serving his one term in Congress. This time Wilmot's amendment, added to a spending bill, moved on to the Senate, where a firestorm broke out. Battles Over the Wilmot Proviso Southerners were deeply offended by the House of Representatives adopting the Wilmot Proviso, and newspapers in the South wrote editorials denouncing it. Some state legislatures passed resolutions denouncing it. Southerners considered it an insult to their way of life. It also raised Constitutional questions. Did the federal government possess the power to restrict slavery in new territories? The powerful senator from South Carolina, John C. Calhoun, who had challenged federal power years earlier in the Nullification Crisis, made forceful arguments on behalf of the slave states. Calhoun’s legal reasoning was that slavery was legal under the Constitution, and slaves were property, and the Constitution protected property rights. Therefore settlers from the South, if they moved to the West, should be able to bring their own property, even if the property happened to be slaves. In the North, the Wilmot Proviso became a rallying cry. Newspapers printed editorials praising it, and speeches were given in support of it. Continuing Effects of the Wilmot Proviso The increasingly bitter debate over whether slavery would be allowed to exist in the West continued through the late 1840s. For several years the Wilmot Proviso would be added to bills passed by the House of Representatives, but the Senate always refused to pass any legislation containing the language about slavery. The stubborn revivals of Wilmot's amendment served a purpose as it kept the issue of slavery alive in Congress and thus before the American people. The issue of slavery in the territories acquired during the Mexican War was finally addressed early in 1850 in a series of Senate debates, which featured the legendary figures Henry Clay, John C. Calhoun, and Daniel Webster. A set of new bills, which would become known as the Compromise of 1850, was thought to have provided a solution. The issue, however, did not die completely. One response to the Wilmot Proviso was the concept of “popular sovereignty,” which was first proposed by a Michigan senator, Lewis Cass, in 1848. The idea that settlers in the state would decide the issue became a constant theme for Senator Stephen Douglas in the 1850s. In the 1848 president, the Free Soil party formed and embraced the Wilmot Proviso. The new party nominated a former president, Martin Van Buren, as its candidate. Van Buren lost the election, but it demonstrated that debates about restricting slavery would not fade away. The language introduced by Wilmot continued to influence anti-slavery sentiment which developed in the 1850s and helped lead to the creation of the Republican Party. And ultimately the debate over slavery could not be solved in the halls of Congress and was only settled by the Civil War.