The advocates of the war had, however, to face at its outset one powerful and unexpected defection, that of Calhoun. No man had been more eager than he for the annexation of Texas, but, Texas once annexed, he showed a marked desire to settle all outstanding questions with Mexico quickly and by a compromise on easy terms. He did all he could to avert war. When war actually came, he urged that even the military operations of the United States should be strictly defensive, that they should confine themselves to occupying the disputed territory and repelling attacks upon it, but should under no circumstances attempt a counter-invasion of Mexico. There can be little doubt that Calhoun's motive in proposing this curious method of conducting a war was, as usual, zeal for the interests of his section, and that he acted as he did because he foresaw the results of an extended war more correctly than did most Southerners. He had coveted Texas because Texas would strengthen the position of the South. Slavery already existed there, and no one doubted that if Texas came into the Union at all it must be as a Slave State. But it would be otherwise if great conquests were made at the expense of Mexico. Calhoun saw clearly that there would be a strong movement to exclude Slavery from such conquests, and, having regard to the numerical superiority of the North, he doubted the ability of his own section to obtain in the scramble that must follow the major part of the spoil.
Calhoun, however, was as unable to restrain by his warnings the warlike enthusiasm of the South as were the little group of Peace Whigs in New England to prevent the North from being swept by a similar passion. Even Massachusetts gave a decisive vote for war.
The brief campaign was conducted with considerable ability, mainly by Generals Taylor and Scott. Such army as Mexico possessed was crushingly defeated at Monterey. An invasion followed, and the fall of Mexico City completed the triumph of American arms. By the peace dictated in the captured capital Mexico had, of course, to concede the original point of dispute in regard to the Texan frontier. But greater sacrifices were demanded of her, though not without a measure of compensation. She was compelled to sell at a fixed price to her conqueror all the territory to which she laid claim on the Pacific slope north of San Diego. Thus Arizona, New Mexico, and, most important of all, California passed into American hands.
But before this conclusion had been reached a significant incident justified the foresight of Calhoun. Towards the close of the campaign, a proposal made in Congress to grant to the Executive a large supply to be expended during the recess at the President's discretion in purchasing Mexican territory was met by an amendment moved by a Northern Democrat named Wilmot, himself an ardent supporter of the war, providing that from all territory that might be so acquired from Mexico Slavery should be for ever excluded. The proviso was carried in the House of Representatives by a majority almost exactly representative of the comparative strength of the two sections. How serious the issue thus raised was felt to be is shown by the fact that the Executive preferred dispensing with the money voted to allowing it to be pushed further. In the Senate both supply and condition were lost. But the "Wilmot Proviso" had given the signal for a sectional struggle of which no man could foresee the end.
Matters were further complicated by a startlingly unexpected discovery. On the very day on which peace was proclaimed, one of the American settlers who had already begun to make their way into California, in digging for water on his patch of reclaimed land, turned up instead a nugget of gold. It was soon known to the ends of the earth that the Republic had all unknowingly annexed one of the richest goldfields yet discovered. There followed all the familiar phenomena which Australia had already witnessed, which South Africa was later to witness, and which Klondyke has witnessed in our time. A stream of immigrants, not only from every part of the United States but from every part of the civilized world, began to pour into California drunk with the hope of immediate and enormous gains. Instead of the anticipated gradual development of the new territory, which might have permitted considerable delay and much cautious deliberation in the settlement of its destiny, one part of that territory at least found itself within a year the home of a population already numerous enough to be entitled to admission to the Union as a State, a population composed in great part of the most restless and lawless of mankind, and urgently in need of some sort of properly constituted government.
A Convention met to frame a plan of territorial administration, and found itself at once confronted with the problem of the admission or exclusion of Slavery. Though many of the delegates were from the Slave States, it was decided unanimously to exclude it. There was nothing sentimentally Negrophil about the attitude of the Californians; indeed, they proclaimed an exceedingly sensible policy in the simple formula: "No Niggers, Slave or Free!" But as regards Slavery their decision was emphatic and apparently irreversible.
The Southerners were at once angry and full of anxiety. It seemed that they had been trapped, that victories won largely by Southern valour were to be used to disturb still more the balance already heavily inclining to the rival section. In South Carolina, full of the tradition of Nullification, men already talked freely of Secession. The South, as a whole, was not yet prepared for so violent a step, but there was a feeling in the air that the type of civilization established in the Slave States might soon have to fight for its life.
On the top of all this vague unrest and incipient division came a Presidential election, the most strangely unreal in the whole history of the United States. The issue about which alone all men, North and South, were thinking was carefully excluded from the platforms and speeches of either party. Everyone of either side professed unbounded devotion to the Union, no one dared to permit himself the faintest allusion to the hot and human passions which were patently tearing it in two. The Whigs, divided on the late war, divided on Slavery, divided on almost every issue by which the minds of men were troubled, yet resolved to repeat the tactics which had succeeded in 1840. And the amazing thing is that they did in fact repeat them and with complete success. They persuaded Zachary Taylor, the victor of Monterey, to come forward as their candidate. Taylor had shown himself an excellent commander, but what his political opinions might be no-one knew, for it transpired that he had never in his life even recorded a vote. The Whigs, however, managed to extract from him the statement that if he had voted at the election of 1844—as, in fact, he had not—it would have been for Clay rather than for Polk; and this admission they proceeded, rather comically, to trumpet to the world as a sufficient guarantee from "a consistent and truth-speaking man" of the candidate's lifelong devotion to "Whig" principles. Nothing further than the above remark and the frank acknowledgment that he was a slave-owner could be extracted from Taylor in the way of programme or profession of faith. But the Convention adopted him with acclamation. Naturally such a selection did not please the little group of Anti-War Whigs—a group which was practically identical with the extreme Anti-Slavery wing of the party—and Lowell, in what is perhaps the most stinging of all his satires, turned Taylor's platform or absence of platform to ridicule in lines known to thousands of Englishmen who know nothing of their occasion:—
"Ez fer my princerples, I glory
In hevin' nothin' of the sort.
I ain't a Whig, I ain't a Tory,
I'm jest a—Candidate in short."
"Monterey," however, proved an even more successful election cry than "Tippercanoe." The Democrats tried to play the same game by putting forward General Cass, who had also fought with some distinction in the Mexican War and had the advantage—if it were an advantage—of having really proved himself a stirring Democratic partisan as well. But Taylor was the popular favourite, and the Whigs by the aid of his name carried the election.