Edward L. Pierce, Memoir and letters of Charles Sumner: volume 3

[161] slavery into a closer and fiercer conflict than before. The latter, emboldened by recent triumphs, set up with greater audacity than ever their pro-slavery theory of the Constitution, maintaining that it carried slavery into all national territories, and established it there beyond the power of Congress or of the inhabitants to abolish it; and they were turbulent and defiant, threatening disunion and armed resistance if their alleged right of dominion should be denied. In the midst of this turmoil and uncertainty, when Northern votes in Congress were shifting, and political leaders were hiding behind subterfuges, there was an uprising in the free States which defeated the Clayton compromise, forced the organization of Oregon as a free territory, and reserved the question as to California and New Mexico for a popular agitation.¹

The Democratic national convention meeting at Baltimore in May, 1848, nominated Lewis Cass for President. He had been an unhesitating partisan of the annexation of Texas and of the Mexican War; and though professing himself at one time to be in favor of the Wilmot Proviso, he avowed a change of mind as the time for the selection of a candidate approached, and was now fully committed against any legislation by Congress on the subject of slavery in the territories. No Northern politician was ever more abject in his submission to Southern dictation. The convention abstained from an explicit declaration on the vexed question, but its resolutions in their general drift indicated an entire accord with the opinions and purposes of the slaveholding class. Its proceedings met with a vigorous protest from a contesting delegation from New York,—the ‘Barnburners,’ as they were called, who immediately after its adjournment organized a formidable revolt in that State. This division of the Democratic party was compounded of uncongenial elements,—some of its adherents acting under genuine antislavery convictions, while others (the larger number, as it was proved by their action four years later) avowed them only as a cover for a purpose to revenge Van Buren's rejection in 1844, or were inspired by partisan animosities growing out of the strifes of New York politics.