I
THE APPROACH OF WAR

Upon the annexation of Texas (in 1845) Mexico at once severed her diplomatic relations with the United States. This result had been foreshadowed by the utterances of Mexican officials dating from the revival of the question in 1843. The relations, however, of the two countries had been difficult to adjust from the time when Mexico became independent in 1821. The most serious friction between them arose concerning four subjects: claims of the United States citizens on the government of Mexico; assistance given the Texans by the people of the United States; violation of Mexican territory by United States troops; and the annexation of Texas.
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The immediate occasion, however, of the breach of diplomatic relations in 1845 was the annexation of Texas. When rumors of the renewal of the annexation movement came to the city of Mexico in the summer of 1843, President Santa Anna gave notice to the United States government, in a letter dated August 23d, from Secretary of State Bocanegra to Minister Waddy Thompson, that “the Mexican government will consider equivalent to a declaration of war against the Mexican Republic the passage of an act for the incorporation of Texas with the territory of the United States; the certainty of the fact184 being sufficient for the immediate proclamation of war, leaving to the civilized world to determine with regard to the justice of the cause of the Mexican Nation, in a struggle which it has been so far from provoking.”101

Thompson replied immediately with a sharply resentful letter, questioning the sources of information of the Mexican authorities as to the prospect of annexation, but refusing any explanation whatever. Another letter from Bocanegra to Thompson asserted that the advices of the Mexican government on the subject were official and reliable, and sought to justify the attitude of Mexico as follows: “but as it may happen that ambition and delusion may prevail over public propriety, that personal views may triumph over sane and just ideas, and that the vigorous reasoning of Mr. John Quincy Adams and his co-laborers may be ineffectual, how can it be considered strange and out of the way that Mexico, under such a supposition, should announce that she will regard the annexation of Texas as an act of declaration of war?”102 Secretary of State Upshur approved the course of Thompson, and instructed him that, in case he were again addressed in such offensive language, he should demand either a withdrawal of the letter or a suitable apology.

On November 3, 1843, Almonte, the Mexican minister at Washington, in accordance with the instructions of his government, notified Upshur, in a communication whose terms were hardly less offensive than those used by Bocanegra to Thompson, that if “the United States should, in defiance of good faith and of the principles of justice which they have constantly proclaimed, commit the unheard-of act of violence (inaudito atentado—the expression [says the official translator] is much stronger than the translation) of appropriating to themselves an integrant part of the Mexican territory, the undersigned, in the185 name of his Nation, and now for them, protests, in the most solemn manner, against such an aggression; and he moreover declares, by express order of his Government, that, on sanction being given by the Executive of the union to the incorporation of Texas into the United States, he will consider his mission ended, seeing that, as the Secretary of State will have learned, the Mexican Government is resolved to declare war so soon as it receives information of such an act.” On November 8th Upshur replied, in a restrained and dignified way, repelling both the threats and insinuations of Almonte’s letter and intimating that the policy of the United States would not be affected by them.103 To this Almonte rejoined, on the 11th, suggesting that Upshur had been misled by an incorrect translation of the letter of November 3d, and disclaiming any intention to impute to the authorities of the American union unworthy views or designs as to Texas. December 1, 1843, Upshur replied, denying that he had misunderstood Almonte, and declaring that the United States regarded Texas as an independent nation and did not feel called on to consult any other nation in dealing with it.104

On the accomplishment of annexation, the threat of Almonte was carried out. The joint resolution making the offer was approved March 1, 1845, and on March 6th he demanded his passports. March 28th the United States minister in Mexico was officially notified that the diplomatic intercourse between the two countries was at an end.105 The expressions of the Mexican papers indicated the most intense popular excitement in that country, and those of the government treated the war as already existing.106 Two decrees were passed by the Mexican congress and approved by President Herrera, one on June 4th and186 the other on June 7th, providing for an increase of the available force in order to resist annexation.107 July 20th the “supreme government,” or executive, recommended to the congress a declaration of war against the United States from the moment when the government should know that annexation had been effected or Texas had been invaded.

There can be little question, indeed, that impatience on both sides had gone beyond the point of safety and was threatening appeal to arms. No theory of a conspiracy is needed to explain the war with Mexico. While it was strongly opposed and condemned by a bold and outspoken minority, the votes in Congress and the utterances of the contemporaneous journals show that it was essentially a popular movement, both in Mexico and in the United States. The disagreement reached the verge of an outbreak in 1837, and the only thing that prevented a conflict then was that Congress was a bit more conservative than the President; but neither the aggressiveness of Jackson nor even that of Polk would have been so likely to end in actual fighting had it not been well understood that they were backed by sympathetic majorities. On the Mexican side, at the critical moment, the pacific tendencies of the executive were overpowered by the angry impulse of the people.

May 28, 1845, General Taylor, who was in command of the troops in the Southwest, was ordered, in view of the prospect of annexation, to hold himself in readiness to advance into Texas with the approval of the Texan authorities, and to defend that republic from any invasion of which he should be officially informed after Texas had consented to annexation on the terms offered. June 15th he was ordered to advance, with the western frontier of Texas for his ultimate destination. There he was to occupy a convenient point “on or near the Rio Grande,”187 but to limit himself to the defence of the territory of Texas unless Mexico should declare war against the United States. He was subsequently directed to protect the territory up to the Rio Grande, avoiding, however, except in case of an outbreak of hostilities, any attack on posts actually held by Mexicans, but placing at least a part of his forces west of the Nueces.108 In July, General Taylor advanced into Texas, and in August he established his camp on the west bank of the Nueces, near Corpus Christi.109 The spot which he selected could hardly be considered as “near” the Rio Grande, being, in fact, about one hundred and fifty miles therefrom. The location was chosen because of its convenience as a temporary base either for defensive or offensive operations.

The army remained in camp near Corpus Christi several months. The information Taylor obtained here and reported to Washington indicated no threatening movement on the part of the Mexicans; but on October 4th he suggested that, if the United States government meant to insist on the Rio Grande as the boundary, it would gain an advantage by occupying points on that river. He therefore suggested an advance to Point Isabel and Laredo.110 Meanwhile had come the attempt to renew diplomatic relations between the United States and Mexico, which ended in failure. January 13, 1846, when it was known in Washington that Slidell would probably not be received by the Mexican government, Taylor was ordered to advance to the Rio Grande.111

Up to the time of this movement the Mexican government had neglected the distinction in the validity of its claims to the territory east of the Rio Grande. It strenuously188 asserted the right of Mexico to the whole of Texas, whatever its limits might be, and declared that annexation would be tantamount to a declaration of war. From the Mexican point of view, Taylor invaded Mexico the moment he entered Texas. But when he advanced to the Rio Grande the distinction was finally made. April 12, 1846, he was warned by Ampudia, general in command of the Mexican forces at Matamoras, to retire in twenty-four hours—not beyond the Sabine, as one might have expected from the previous attitude of the Mexican government, but beyond the Nueces.112

A few days later occurred the first conflict. April 24th a party of dragoons sent out by Taylor was ambushed on the east side of the river by a large force of Mexicans, and after a skirmish, in which a number of men were killed and wounded, was captured.113 The official report of this affair reached Washington the evening of Saturday, May 9th.114 President Polk had already decided, in conformity with the judgment of all his cabinet except Bancroft, to send to Congress a message recommending a declaration of war. Now, in formulating the reasons for the declaration, he asserted that “Mexico has passed the boundary of the United States, has invaded our territory, and shed American blood upon the American soil,”115 and with the unanimous concurrence of his cabinet he sent the message to Congress, Monday, May 11th.

On the same day a bill providing for the enlistment of fifty thousand soldiers and the appropriation of ten million dollars, the preamble to which re-echoed the President’s assertion that war existed by the act of Mexico itself, passed the House by a vote of 174 to 14.116

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II
CONQUERING A PEACE (1846–1848)

It was only after Polk felt assured of the refusal to receive Slidell117 that he assumed an attitude so aggressive as clearly to challenge war; and from that time forward it seems to have been his desire to carry the struggle just far enough to bring Mexico to the point of conceding a territorial indemnity on the terms which he had intended to offer through Slidell. In accordance with this policy he suggested, while the question of Slidell’s reception by the Paredes government was yet in suspense, that Slidell should be directed to go on board a United States vessel and wait for further instructions.118 The object of this plan was evidently to be able to resume negotiations, as soon as Mexico had felt the pressure sufficiently, without the delays incident to a correspondence between the two capitals. The same considerations influenced, at a later stage of ............