Reasons for War (1846)

The existing state of the relations between the United States and Mexico renders it proper that I should bring the subject to the consideration of Congress. In my message at the commencement of your present session the state of these relations, the causes which led to the suspension of diplomatic intercourse between the two countries in March 1845, and the long-continued and unredressed wrongs and injuries committed by the Mexican Government on citizens of the United States in their persons and property were briefly set forth.

Mr. Slidell arrived at Vera Cruz on the 30th of November [1845] and was courteously received by the authorities of that city. But the Government of General Herrera was then tottering to its fall. The revolutionary party had seized upon the Texas question to effect or hasten its overthrow. Its determination to restore friendly relations with the United States and to receive our minister to negotiate for the settlement of this question was violently assailed and was made the great theme of denunciation against it. The Government of General Herrera, there is good reason to believe, was sincerely desirous to receive our minister but it yielded to the storm raised by its enemies and on the 21st of December refused to accredit Mr. Slidell upon the most frivolous pretexts. These are so fully and ably exposed in the note of Mr. Slidell of the 24th of December last to the Mexican minister of foreign relations that I deem it unnecessary to enter into further detail on this portion of the subject.

Five days after the date of Mr. Slidell's note General Herrera yielded the Government to General Paredes without a struggle and on the 30th of December resigned the Presidency. This revolution was accomplished solely by the army, the people having taken little part in the contest. And thus the supreme power in Mexico passed into the hands of a military leader.

Thus the Government of Mexico, though solemnly pledged by official acts in October last to receive and accredit an American envoy, violated their plighted faith and refused the offer of a peaceful adjustment of our difficulties. Not only was the offer rejected but the indignity of its rejection was enhanced by the manifest breach of faith in refusing to admit the envoy who came because they had bound themselves to receive him. Nor can it be ascribed to a want of sufficient powers; our envoy had full powers to adjust every question of difference. Nor was there room for complaint that our propositions for settlement were unreasonable. Nor can it be objected that we, on our part, would not listen to any reasonable terms of their suggestion; the Mexican Government refused all negotiation and have made no proposition of any kind.

In my message at the commencement of the present session I informed you that upon the earnest appeal both of the Congress and convention of Texas I had ordered an efficient military force to take a position "between the Nueces and the Del Norte [Rio Grande]". This had become necessary to meet a threatened invasion of Texas by the Mexican forces, for which extensive military preparations had been made. The invasion was threatened solely because Texas had determined in accordance with a solemn resolution of the Congress of the United States, to annex herself to our Union and under these circumstances it was plainly our duty to extend our protection over her citizens and soil.

This force was concentrated at Corpus Christi and remained there until after I had received such information from Mexico as rendered it probable if not certain that the Mexican Government would refuse to receive our envoy. Meantime Texas, by the final action of our Congress, had become an integral part of our Union. The Congress of Texas by its act of December 19 1836 had declared the Rio del Norte to be the boundary of that Republic. Its jurisdiction had been extended and exercised beyond the Nueces. The country between that river and the Del Norte had been represented in the Congress and in the convention of Texas, had thus taken part in the act of annexation itself, and is now included within one of our Congressional districts. Our own Congress had moreover, with great unanimity by the act approved December 31 1845, recognized the country beyond the Nueces as a part of our territory by including it within our own revenue system and a revenue officer to reside within that district has been appointed by and with the advice and consent of the Senate. It became therefore of urgent necessity to provide for the defense of that portion of our country. Accordingly on the 13th of January last instructions were issued to the general in command of these troops to occupy the left bank of the Del Norte. This river, which is the southwestern boundary of the State of Texas, is an exposed frontier.

The movement of the troops to the Del Norte was made by the commanding general under positive instructions to abstain from all aggressive acts toward Mexico or Mexican citizens and to regard the relations between that Republic and the United States as peaceful unless she should declare war or commit acts of hostility indicative of a state of war. He was specially directed to protect private property and respect personal rights. The Army moved from Corpus Christi on the 11th of March and on the 28th of that month arrived on the left bank of the Del Norte opposite to Matamoras, where it encamped on a commanding position which has since been strengthened by the erection of fieldworks. A depot has also been established at Point Isabel near the Brazos Santiago, 30 miles in rear of the encampment. The selection of his position was necessarily confided to the judgment of the general in command.

The Mexican forces at Matamoras assumed a belligerent attitude and on the 13th of April General Ampudia, then in command, notified General Taylor to break up his camp within twenty-four hours and to retire beyond the Nueces River and in the event of his failure to comply with these demands announced that arms and arms alone must decide the question. But no open act of hostility was committed until the 24th of April. On that day General Arista, who had succeeded to the command of the Mexican forces, communicated to General Taylor that "he considered hostilities commenced and should prosecute them." A party of dragoons of 63 men and officers were on the same day dispatched from the American camp up the Rio del Norte on its left bank to ascertain whether the Mexican troops had crossed or were preparing to cross the river, “became engaged with a large body of these troops and after a short affair in which some 16 were killed and wounded, appear to have been surrounded and compelled to surrender.”

The grievous wrongs perpetrated by Mexico upon our citizens throughout a long period of years remain un-redressed and solemn treaties pledging her public faith for this redress have been disregarded. A government either unable or unwilling to enforce the execution of such treaties fails to perform one of its plainest duties. Our commerce with Mexico has been almost annihilated. It was formerly highly beneficial to both nations but our merchants have been deterred from prosecuting it by the system of outrage and extortion which the Mexican authorities have pursued against them, whilst their appeals through their own Government for indemnity have been made in vain. Our forbearance has gone to such an extreme as to be mistaken to its character. Had we acted with vigor in repelling the insults and redressing the injuries inflicted by Mexico at the commencement, we should doubtless have escaped all the difficulties in which we are now involved.

Instead of this however, we have been exerting our best efforts to propitiate her good will. Upon the pretext that Texas, a nation as independent as herself, thought proper to unite its destinies with our own, she has affected to believe that we have severed her rightful territory and in official proclamations and manifestoes has repeatedly threatened to make war upon us for the purpose of reconquering Texas. In the meantime we have tried every effort at reconciliation. The cup of forbearance had been exhausted even before the recent information from the frontier of the Del Norte. But now, after reiterated menaces Mexico has passed the boundary of the United States, has invaded our territory, and shed American blood upon the American soil. She has proclaimed that hostilities have commenced and that the two nations are now at war.

As war exists and notwithstanding all our efforts to avoid it exists by the act of Mexico herself, we are called upon by every consideration of duty and patriotism to vindicate with decision the honor, the rights, and the interests of our country.

Source: "Reasons for War" (1846), by James Knox Polk, in James D. Richardson, A Compilation of the Messages and Papers of the Presidents (1897), IV, 437-442. https://archive.org/details/americanhistoryt00ivunse/page/20/mode/2up