Conflict with Mexico prompted debates over the Polk administration’s aggressive efforts to acquire territory and spread slavery. Here, Polk’s critics face off against the expansionists.

John L. O’Sullivan, Editor

“Manifest Destiny,” from United States Magazine and Democratic Review, July 1845

Texas is now ours … [Britain and France tried] to intrude themselves [into Texas affairs] … for the avowed object of thwarting our policy and hampering our power, limiting our greatness and checking the fulfillment of our manifest destiny to overspread the continent allotted by Providence for the free development of our yearly multiplying millions. …

The independence of Texas was complete and absolute. It was an independence, not only in fact, but of right. … What then can be more preposterous than all this clamor by Mexico and the Mexican interest, against Annexation, as a violation of any rights of hers … ?

Nor is there any just foundation for the charge that Annexation is a great pro-slavery measure — calculated to increase and perpetuate that institution. Slavery had nothing to do with it. … That it will tend to facilitate and hasten the disappearance of Slavery from all the northern tier of the present Slave States, cannot surely admit of serious question. The greater value in Texas of the slave labor now employed in those States, must soon produce the effect of draining off that labor southwardly. …

California will, probably, next fall away. … Already the advance guard of the irresistible army of Anglo-Saxon emigration has begun to pour down upon it, armed with the plough and the rifle, and marking its trail with schools and colleges, courts and representative halls, mills and meeting-houses. A population will soon be in actual occupation of California. … And they will have a right to independence — to self-government … a better and a truer right than the artificial title of sovereignty in Mexico, a thousand miles distant, inheriting from Spain a title good only against those who have none better.

Source: Sean Wilentz, ed., Major Problems in the Early Republic, 1787–1848 (Lexington, MA: D. C. Heath, 1991), 525–528.

James Buchanan, U.S. Secretary of State

Letter to John Slidell, Minister Plenipotentiary to Mexico, November 1845

In your negotiations with Mexico, the independence of Texas must be considered a settled fact, and is not to be called in question. …

It may, however, be contended on the part of Mexico, that the Nueces and not the Rio del Norte [Rio Grande], is the true western boundary of Texas. I need not furnish you arguments to controvert this position. … The jurisdiction of Texas has been extended beyond that river [the Nueces] and … representatives from the country between it and the Del Norte have participated in the deliberations both of her Congress and her Convention. …

The case is different in regard to New Mexico. Santa Fe, its capital, was settled by the Spaniards more than two centuries ago; and that province has been ever since in their possession and that of the Republic of Mexico. The Texans never have conquered or taken possession of it. … [However,] a great portion of New Mexico being on this side of the Rio Grande and included within the limits already claimed by Texas, it may hereafter, should it remain a Mexican province, become a subject of dispute. … It would seem to be equally the interest of both Powers, that New Mexico should belong to the United States. …

It is to be seriously apprehended that both Great Britain and France have designs upon California. … This Government … would vigorously interpose to prevent the latter from becoming either a British or a French Colony. … The possession of the Bay and harbor of San Francisco, is all important to the United States. … Money would be no object.

Source: Victoria Bissell Brown and Timothy J. Shannon, eds., Going to the Source: The Bedford Reader in American History (Boston: Bedford/St. Martin’s, 2004), 1: 260–262.

Charles Sumner, Conscience Whig and Future Republican Senator from Massachusetts

Letter to Robert Winthrop, Whig Congressman from Massachusetts, October 25, 1846

If we regard Texas as a province of Mexico, its boundaries must be sought in the geography of that republic. If we regard it as an independent State, they must be determined by the extent of jurisdiction which the State was able to maintain. Now it seems clear that the river Nueces was always recognized by Mexico as the western boundary; and it is undisputed that the State of Texas, since its Declaration of Independence, never exercised any jurisdiction beyond the Nueces. …

In the month of January, 1846, the President of the United States directed the troops under General Taylor, called the Army of Occupation, to take possession of this region [west of the Nueces River]. Here was an act of aggression. As might have been expected, it produced collision. The Mexicans, aroused in self-defence, sought to repel the invaders. …

Here the question occurs, What was the duty of Congress in this emergency? Clearly to withhold all sanction to unjust war, — to aggression upon a neighboring Republic. … The American forces should have been directed to retreat, not from any human force, but from wrongdoing; and this would have been a true victory.

Alas! This was not the mood of Congress. With wicked speed a bill was introduced, furnishing large and unusual supplies of men and money. … This was adopted by a vote of 123 to 67; and the bill then leaped forth, fully armed, as a measure of open and active hostility against Mexico.

Source: Sean Wilentz, ed., Major Problems in the Early Republic, 1787–1848 (Lexington, MA: D. C. Heath, 1991), 541.

Walt Whitman, Poet and Editor of the Brooklyn Eagle

Editorial, September 1, 1847

The question whether or no there shall be slavery in the new territories … is a question between the grand body of white workingmen, the millions of mechanics, farmers, and operatives of our country, with their interests on the one side — and the interests of the few thousand rich, “polished,” and aristocratic owners of slaves at the South, on the other side.

Experience has proved … that a stalwart mass of respectable workingmen, cannot exist, much less flourish, in a thorough slave State. Let any one think for a moment what a different appearance New York, Pennsylvania, or Ohio, would present — how much less sturdy independence and family happiness there would be — were slaves the workmen there, instead of each man as a general thing being his own workman. …

Slavery is a good thing enough … to the rich — the one out of thousands; but it is destructive to the dignity and independence of all who work, and to labor itself. … All practice and theory … are strongly arrayed in favor of limiting slavery to where it already exists.

Source: Sean Wilentz, ed., Major Problems in the Early Republic, 1787–1848 (Lexington, MA: D. C. Heath, 1991), 543.