Wilmot Proviso - Aftermath

Aftermath

With the approval of the treaty, the issue moved from one of abstraction to one involving practical matters. The nature of the Constitution, slavery, the value of free labor, political power, and ultimately political realignment were all involved in the debate. Historian Michael Morrison argues that from 1820 to 1846 a combination of "racism and veneration of the Union" had prevented a direct northern attack on slavery. While the original southern response to the Wilmot Proviso was measured, it soon became clear to the South that this long postponed attack on slavery had finally occurred. Rather than simply the politics of the issue, historian William Freehling noted, "Most Southerners raged primarily because David Wilmot’s holier-than-thou stance was so insulting."

In the North, the most immediate repercussions involved Martin Van Buren and the state of New York. The Barnburners were successfully opposed by their conservative opposition, the Hunkers, in their efforts to send a pro-proviso batch of delegates to the 1848 Democratic National Convention. The Barnburners held their own separate convention and sent their own slate of delegates to the convention in Baltimore. Both delegations were seated with the state's total votes split between them. When the convention rejected a pro-proviso plank and selected Lewis Cass as the nominee, the Barnburners again bolted and were the nucleus of forming the Free Soil Party. Historian Leonard Richards writes of these disaffected Democrats:

Overall, then, Southern Democrats during the 1840s lost the hard core of their original doughface support. No longer could they count on New England and New York Democrats to provide them with winning margins in the House. …
To them the movement to acquire Texas, and the fight over the Wilmot Proviso, marked the turning point, when aggressive slavemasters stole the heart and soul of the Democratic Party and began dictating the course of the nation’s destiny.

Historian William Cooper presents the exactly opposite southern perspective:

Southern Democrats, for whom slavery had always been central, had little difficulty in perceiving exactly what the proviso meant for them and their party. In the first place the mere existence of the proviso meant the sectional strains that had plagued the Whigs on Texas now beset the Democrats on expansion, the issue the Democrats themselves had chosen as their own. The proviso also announced to southerners that they had to face the challenge of certain northern Democrats who indicated their unwillingness to follow any longer the southern lead on slavery. That circumstance struck at the very roots of the southern conception of party. The southerners had always felt that their northern colleagues must toe the southern line on all slavery-related issues.

In Alabama, with no available candidate sufficiently opposed to the proviso, William L. Yancey secured the adoption by the state Democratic convention of the so-called "Alabama Platform", which was endorsed by the legislatures of Alabama and Georgia and by Democratic state conventions in Florida and Virginia. The platform called for no Federal restrictions of slavery in the territories, no restrictions on slavery by territorial governments until the point where they were drafting a state constitution in order to petition Congress for statehood, opposition to any candidates supporting either the proviso or popular sovereignty, and positive federal legislation overruling Mexican anti-slavery laws in the Mexican Cession. However the same Democratic Convention that had refused to endorse the proviso also rejected incorporating the Yancey proposal into the national platform by a 216–36 vote. Unlike the Barnburner walkout, however, only Yancey and one other Alabama delegate left the convention. Yancey’s efforts to stir up a third party movement in the state failed.

Southerner Whigs looked hopefully to slaveholder and war hero General Zachary Taylor as the solution to the widening sectional divide even though he took no public stance on the Wilmot Proviso. However Taylor, once nominated and elected, showed that he had his own plans. Taylor hoped to create a new non-partisan coalition that would once again remove slavery from the national stage. He expected to be able to accomplish this by freezing slavery at its 1849 boundaries and by immediately bypassing the territory stage and creating two new states out of the Mexican Cession.

The opening salvo in a new level of sectional conflict occurred on December 13, 1848 when John G. Palfrey (Whig) of Massachusetts introduced a bill to abolish slavery in the District of Columbia. Throughout 1849 in the South "the rhetoric of resistance to the North escalated and spread". The potentially secessionist Nashville Convention was scheduled for June 1850. When President Taylor in his December 1849 message to Congress urged the admission of California as a free state, a state of crisis was further aggravated. Historian Allan Nevins sums up the situation which had been created by the Wilmot Proviso:

Thus the contest was joined on the central issue which was to dominate all American history for the next dozen years, the disposition of the Territories. Two sets of extremists had arisen: Northerners who demanded no new slave territories under any circumstances, and Southerners who demanded free entry for slavery into all territories, the penalty for denial to be secession. For the time being, moderates who hoped to find a way of compromise and to repress the underlying issue of slavery itself – its toleration or non-toleration by a great free Christian state – were overwhelmingly in the majority. But history showed that in crises of this sort the two sets of extremists were almost certain to grow in power, swallowing up more and more members of the conciliatory center.

Combined with other slavery related issues, the Wilmot Proviso led to the Compromise of 1850, which helped buy another shaky decade of peace. Radical secessionists were temporarily at bay as the Nashville Convention failed to endorse secession. Moderates rallied around the Compromise as the final solution to the sectional issues involving slavery and the territories. At the same time, however, the language of the Georgia Platform, widely accepted throughout the South, made it clear that the South’s commitment to Union was not unqualified; they fully expected the North to adhere to their part of the agreement.