Besides these main operations, there were various collateral movements designed to cripple the power and diminish the territory of Mexico. General Kearney, with an independent force of volunteers, had marched into and taken possession of the province of New Mexico; Colonel Doliphan had in like manner occupied Chihuahua; while Colonel Fremont, placing himself at the head of a band of American settlers recruited in the valley of the Sacramento, and supported by Commodore Stockton, had availed himself of the opportunity to hold Upper California for the United States. [Sidenote: The Treaty of Peace.] Thus Mexico was subdued and compelled to come to terms, her enemy dictating these from her own capital. Commissioners met at the city of Guadalupe Hidalgo to conclude a treaty of peace. By this instrument Mexico agreed to accept the Rio Grande as the boundary between herself and Texas, adding thereby to the territory of the United States an area of not less than five hundred thousand square miles; to make over New Mexico and Upper California to the United States in consideration of the sum of fifteen millions of dollars; and to guarantee the debts due from Mexico to American citizens. This treaty was duly ratified and exchanged in the spring of 1848--about two years after the beginning of hostilities. [Sidenote: Political Effect of the War.] [Sidenote: California.] The political effect of the Mexican War was to add a large territory and a fast-increasing population to the tier of slave-holding States, and thus to aggrandize the slave-holding oligarchy, as opposed to the party in favor of free soil. On the other hand, the military glory won by General Taylor, and his adoption in the year after the war as the Whig candidate for the Presidency, singularly enough brought into power the party which had persistently opposed both the annexation of Texas, and the war which had been undertaken to complete it. The Mexican War provided the parties with four presidential candidates, Generals Taylor, Scott, Pierce, and Fremont, two of whom succeeded in reaching the summit of executive authority. When Colonel Fremont raised the American standard in California, it was little imagined that he was acquiring a province for the country the value of which was destined to be incalculably greater than the Texan republic. Within a year, however, the gold mines had been discovered, and that wonderful civilization of the Pacific Coast which we now witness had begun to grow up in the far western wilderness. XII. THE SLAVERY AGITATION. [Sidenote: Slavery Inherited.]