Constitution, debate waxed hot upon the topic which was then seen to present grave obstacles to union. It was true that many of the wisest Southerners of that generation regarded the institution as a menacing misfortune; they however could not ignore the fact that it was a "misfortune" of that peculiar kind which was endured with much complacency by those afflicted by it; and it was equally certain that the great body of slave-owners would resent any effort to relieve them of their burden. Hence there were placed in the Constitution provisions in behalf of slavery which involved an admission that the institution needed protection, and should receive it. The idea of protection implied the existence of hostility either of men or of circumstances, or of both. Thus by the Ordinance and the Constitution, taken together, there was already indirectly recognized an antagonism between the institutions, interests, and opinions of the South and those of the North.
Slowly this feeling of opposition grew. The first definite mark of the growth was the struggle over the admission of Missouri, in 1820. This was settled by the famous "Compromise," embodied in the Act of March 6, 1820, whereby the people of the Territory of Missouri were allowed to frame a state government with no restriction against slavery; but a clause also enacted that slavery should never be permitted in any part of the remainder of the public territory lying north of the parallel of 36° 30'. By its efficiency during thirty-four years of constantly increasing strain this legislation was proved to be a remarkable political achievement; and as the people saw it perform so long and so well a service so vital they came to regard it as only less sacred than the Constitution itself. Even Douglas, who afterward led in repealing it, declared that it had an "origin akin to the Constitution," and that it was "canonized in the hearts of the American people as a sacred thing." Yet during the long quietude which it brought, each section kept a jealous eye upon the other; and especially was the scrutiny of the South uneasy, for she saw ever more and more plainly the disturbing truth that her institution needed protection. Being in derogation of natural right, it was peculiarly dependent upon artificial sustention; the South would not express the condition in this language, but acted upon the idea none the less. It was true that the North was not aggressive towards slavery, but was observing it with much laxity and indifference; that the crusading spirit was sleeping soundly, and even the proselyting temper was feeble. But this state of Northern feeling could not relieve the South from the harassing consciousness that slavery needed not only toleration, but positive protection at the hands of a population whose institutions were naturally antagonistic to the slave idea. This being the case, she must be alarmed at seeing that population steadily outstripping her own in numbers and wealth.[61] Since she could not possibly even hold this disproportion stationary, her best resource seemed to be to endeavor to keep it practically harmless by maintaining a balance of power in the government. Thus it became unwritten law that slave States and free States must be equal in number, so that the South could not be outvoted in the Senate. This system was practicable for a while, yet not a very long while; for the North was filling up that great northwestern region, which was eternally dedicated to freedom, and full-grown communities could not forever be kept outside the pale of statehood. On the other hand, apart from any question of numbers, the South could make no counter-expansion, because she lay against a foreign country. After a time, however, Texas opportunely rebelled against Mexico, and then the opportunity for removing this obstruction was too obvious and too tempting to be lost. A brief period of so-called independence on the part of Texas was followed by the annexation of her territory to the United States,[62] with the proviso that from her great area might in the future be cut off still four other States. Slavery had been abolished in all Mexican territory, and Texas had been properly a "free" country; but in becoming a part of the United States she became also a slave State.
Mexico had declared that annexation of Texas would constitute a casus belli, yet she was wisely laggard in beginning vindictive hostilities against a power which could so easily whip her, and she probably never would have done so had the United States rested content with an honest boundary line. But this President Polk would not do, and by theft and falsehood he at last fairly drove the Mexicans into a war, in which they were so excessively beaten that the administration found itself able to gather more plunder than it had expected. By the treaty of peace the United States not only extended unjustly the southwestern boundary of Texas, but also got New Mexico and California. To forward this result, Polk had asked the House to place $2,000,000 at his disposal. Thereupon, as an amendment to the bill granting this sum, Wilmot introduced his famous proviso, prohibiting slavery in any part of the territory to be acquired. Repeatedly and in various shapes was the substance of this proviso voted upon, but always it was voted down. Though New Mexico had come out from under the rule of despised Mexico as "free" country, a contrary destiny was marked out for it in its American character. A plausible suggestion was made to extend the sacred line of the Missouri Compromise westward to the Pacific Ocean; and very little of the new country lay north of that line. By all these transactions the South seemed to be scoring many telling points in its game. They were definite points, which all could see and estimate; yet a price, which was considerable, though less definite, less easy to see and to estimate, had in fact been paid for them; for the antagonism of the rich and teeming North to the Southern institution and to the Southern policy for protecting it had been spread and intensified to a degree which involved a menace fully offsetting the Southern territorial gain. One of the indications of this state of feeling was the organization of the "Free Soil" party.
Almost simultaneously with this important advancement of the Southern policy there occurred an event, operative upon the other side, which certainly no statesman could have foreseen. Gold was discovered in California, and in a few months a torrent of immigrants poured over the land. The establishment of an efficient government became a pressing need. In Congress they debated the matter hotly; the friends of the Wilmot proviso met in bitter conflict the advocates of the westward extension of the line of 36° 30'. Neither side could prevail, and amid intense excitement the Thirtieth Congress expired. For the politicians this was well enough, but for the Californians organization was such an instant necessity that they now had to help themselves to it. So they promptly elected a Constitutional Convention, which assembled on September 1, 1849, and adjourned on October 13. Though this body held fifteen delegates who were immigrants from slave States, yet it was unanimous in presenting a Constitution which prohibited slavery, and which was at once accepted by a popular vote of 12,066 yeas against 811 nays.
Great then was the consternation of the Southern leaders when Californian delegates appeared immediately upon the assembling of the Thirty-first Congress, and asked for admission beneath this unlooked-for "free" charter of statehood. The shock was aggravated by the fact that New Mexico, actually instigated thereto by the slaveholding President Taylor himself, was likely to follow close in the Californian foot-tracks. The admission of Texas had for a moment disturbed the senatorial equilibrium between North and South, which, however, had quickly been restored by the admission of Wisconsin. But the South had nothing to offer to counterbalance California and New Mexico, which were being suddenly filched from her confident expectation. In this emergency those extremists in the South who offset the Abolitionists at the North fell back upon the appalling threat of disunion, which could hardly be regarded as an idle extravagance of the "hotspurs," since it was substantially certain that the Senate would never admit California with her anti-slavery Constitution; and thus a real crisis seemed at hand. Other questions also were cast into the seething caldron. Texas, whose boundaries were as uncertain as the ethics of politicians, set up a claim which included nearly all New Mexico, and so would have settled the question of slavery for that region at least. Further, the South called for a Fugitive Slave Law sufficiently stringent to be serviceable. Also, in encountering the Wilmot proviso, Southern statesmen had asserted the doctrine, far-reaching and subversive of established ideas and of enacted laws, that Congress could not constitutionally interfere with the property-rights of citizens of the United States in the Territories, and that slaves were property. Amid such a confused and violent hurly-burly the perplexed body of order-loving citizens were, with reason, seriously alarmed.
To the great relief of these people and to the equal disgust of the extremist politicians, Henry Clay, the "great compromiser," was now announced to appear once more in the rôle which all felt that he alone could play. He came