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.

As the facts and opinions which were then laid before you were care fully considered, I can not better express my present convictions of the condition of affairs up to that time than by referring you to that communication.

The strong desire to establish peace with Mexico on liberal and honorable terms, and the readiness of this Government to regulate and adjust our boundary and other causes of difference with that power on such fair and equitable principles as would lead to permanent relations of the most friendly nature, induced me in September last to seek the reopening of diplomatic relations between the two countries. Every measure adopted on our part had for its object the furtherance of these desired results. In communicating to Congress a succinct statement of the injuries which we had suffered from Mexico, and which have been accumulating during a period of more than twenty years, every expression that could tend to inflame the people of Mexico or defeat or delay a pacific result was carefully avoided. An envoy of the United States repaired to Mexico with full powers to adjust every existing difference. But though present on the Mexican soil by agreement between the two Governments, invested with full powers, and bearing evidence of the most friendly dispositions, his mission has been unavailing. The Mexican Government not only refused to receive him or listen to his propositions, but after a long-continued series of menaces have at last invaded our territory and shed the blood of our fellow-citizens on our own soil.

It now becomes my duty to state more in detail the origin, progress, and failure of that mission. In pursuance of the instructions given in September last, an inquiry was made on the 13th of October, 1845, in the most friendly terms, through our consul in Mexico, of the minister for foreign affairs, whether the Mexican Government would receive an envoy from the United States intrusted with full powers to adjust all the questions in dispute between the two Governments, with the assurance that should the answer be in the affirmative such an envoy would be immediately dispatched to Mexico. The Mexican minister on the I5th of October gave an affirmative answer to this inquiry, requesting at the same time that our naval force at Vera Cruz might be withdrawn, lest its continued presence might assume the appearance of menace and coercion pending the negotiations. This force was immediately withdrawn. On the 10th of November, 1845, Mr. John Slidell, of Louisiana, was commissioned by me as envoy extraordinary and minister plenipotentiary of the United States to Mexico, and was intrusted with full powers to adjust both the questions of the Texas boundary and of indemnification to our citizens. The redress of the wrongs of our citizens naturally and inseparably blended itself with the question of boundary. The settlement of the one question in any correct view of the subject involves that of the other. I could not for a moment entertain the idea that the claims of our much-injured and long-suffering citizens, many of which had existed for more than twenty years, should be postponed or separated from the settlement of the boundary question.

Mr. Slidell arrived at Vera Cruz on the 30th of November, 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, herewith transmitted, 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. Determined to leave no effort untried to effect an amicable adjustment with Mexico, I directed Mr. Slidell to present his credentials to the Government of General Paredes and ask to be officially received by him. There would have been less ground for taking this step had General Paredes come into power by a regular constitutional succession. In that event his administration would have been considered but a mere constitutional continuance of the Government of General Herrera, and the refusal of the latter to receive our minister would have been deemed conclusive unless an intimation had been given by General Paredes of his desire to reverse the decision of his predecessor. But the Government of General Paredes owes its existence to a military revolution, by which the subsisting constitutional authorities had been subverted. The form of government was entirely changed, as well as all the high functionaries by whom it was administered.

Under these circumstances, Mr. Slidell, in obedience to my direction, addressed a note to the Mexican minister of foreign relations, under date of the 1st of March last, asking to be received by that Government in the diplomatic character to which he had been appointed. This minister in his reply, under date of the 12th of March, reiterated the arguments of his predecessor, and in terms that may be considered as giving just grounds of offense to the Government and people of the United States denied the application of Mr. Slidell. Nothing therefore remained for our envoy but to demand his passports and return to his own country.

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 said that the offer was fruitless from the want of opportunity of discussing it; our envoy was present on their own soil. 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; permission was not even given our envoy to make any proposition whatever. 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. 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 I3th 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.

From this quarter invasion was threatened; upon it and in its immediate vicinity, in the judgment of high military experience, are the proper stations for the protecting forces of the Government. In addition to this important consideration, several others occurred to induce this movement. Among these are the facilities afforded by the ports at Brazos Santiago and the mouth of the Del Norte for the reception of supplies by sea, the stronger and more healthful military positions, the convenience for obtaining a ready and a more abundant supply of provisions, water, fuel, and forage, and the advantages which are afforded by the Del Norte in forwarding supplies to such posts as may be established in the interior and upon the Indian 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 12th 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 14th 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 unredressed, 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 in 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.

Anticipating the possibility of a crisis like that which has arrived, instructions were given in August last, as a precautionary measure against invasion or threatened invasion, authorizing General Taylor, if the emergency required, to accept volunteers, not from Texas only, but from the States of Louisiana, Alabama, Mississippi, Tennessee, and Kentucky, and corresponding letters were addressed to the respective governors of those States. These instructions were repeated, and in January last, soon after the incorporation of Texas into our Union of States, General Taylor was further authorized by the President to make a requisition upon the executive of that State for such of its militia force as may be needed to repel invasion or to secure the country against apprehended invasion. On the 2d day of March he was again reminded, in the event of the approach of any considerable Mexican force, promptly and efficiently to use the authority with which he was clothed to call to him such auxiliary force as he might need. War actually existing and our territory having been invaded, General Taylor, pursuant to authority vested in him by my direction, has called on the governor of Texas for four regiments of State troops, two to be mounted and two to serve on foot, and on the governor of Louisiana for four regiments of infantry to be sent to him as soon as practicable.

In further vindication of our rights and defense of our territory, I involve the prompt action of Congress to recognize the existence of the war, and to place at the disposition of the Executive the means of prosecuting the war with vigor, and thus hastening the restoration of peace. To this end I recommend that authority should be given to call into the public service a large body of volunteers to serve for not less than six or twelve months unless sooner discharged. A volunteer force is beyond question more efficient than any other description of citizen soldiers, and it is not to be doubted that a number far beyond that required would readily rush to the field upon the call of their country. I further recommend that a liberal provision be made for sustaining our entire military force and furnishing it with supplies and munitions of war.

The most energetic and prompt measures and the immediate appearance in arms of a large and overpowering force are recommended to Congress as the most certain and efficient means of bringing the existing collision with Mexico to a speedy and successful termination.

In making these recommendations I deem it proper to declare that it is my anxious desire not only to terminate hostilities speedily, but to bring all matters in dispute between this Government and Mexico to an early and amicable adjustment; and in this view I shall be prepared to renew negotiations whenever Mexico shall be ready to receive propositions or to make propositions of her own.

I transmit herewith a copy of the correspondence between our envoy to Mexico and the Mexican minister for foreign affairs, and so much of the correspondence between that envoy and the Secretary of State and between the Secretary of War and the general in command on the Del Norte as is necessary to a full understanding of the subject.