Carl Schurz, in his admirable life of Clay, makes a pertinent summary: “The slaveholders watched with apprehension the steady growth of the Free States in population, wealth, and power.... As the slaveholders had no longer the ultimate extinction, but now the perpetuation, of slavery in view, the question of sectional power became one of first importance to them, and with it the necessity of having more slave States for the purpose of maintaining the political equilibrium, at least in the Senate. A struggle for more slave States was to them a struggle for life.”
Thus the two elements of commercial profit and political power were involved in the struggle of the South for the maintenance and extension of slavery.
The House of Representatives in 1819 adopted the Missouri bill with the amendment restricting slavery, but the Senate did not concur; and Alabama was admitted as a Territory without slavery restriction. In the next Congress Missouri was again introduced, but the antislavery amendment was voted down. In 1820 Mr. Thomas, a senator from Illinois, proposed, as a mutual concession, that Missouri should be admitted without restriction, but that in all that part of the territory outside that State ceded by France to the United States, north of the latitude of 36 deg. 30’ (the southern boundary of Missouri), slaves should thereafter be excluded; and this bill was finally passed March 2,1820. Mr. Clay is credited with being the father of this compromise, but, according to Mr. Schurz, he did not deserve the honor. He adopted it, however, and advocated it with so much eloquence and power that it owed its success largely to his efforts, and therefore it is still generally ascribed to him.
At that time no statesmen, North or South, had fully grasped the slavery question. Even Mr. Calhoun once seemed to have no doubt as to the authority of Congress to exclude slavery from the Territories, but he was decided enough in his opposition when he saw that it involved an irreconcilable conflict of interests,—that slavery and freedom are antagonistic ideas, concerning which there can be no genuine compromise. “There may be compromises,” says Von Holst, “with regard to measures, but never between principles.” And slavery, when the Missouri Compromise was started, was looked upon as a measure rather than as a principle, concerning which few statesmen had thought deeply. As the agitation increased, measures were lost sight of in principles.