Mexico may have chosen to consider, and may still choose to consider, Texas as having been at all times since 1835, and as still continuing, a rebellious province; but the world has been obliged to take a very different view of the matter. From the time of the battle of San Jacinto, in April, 1836, to the present moment, Texas has exhibited the same external signs of national independence as Mexico herself, and with quite as much stability of government. Practically free and independent, acknowledged as a political sovereignty by the principal powers of the world, no hostile foot finding rest within her territory for six or seven years, and Mexico herself refraining for all that period from any further attempt to reestablish her own authority over that territory, it can not but be surprising to find Mr. De Bocanegra [the secretary of foreign affairs of Mexico] complaining that for that whole period citizens of the United States or its Government have been favoring the rebels of Texas and supplying them with vessels, ammunition, and money, as if the war for the reduction of the Province of Texas had been constantly prosecuted by Mexico, and her success prevented by these influences from abroad.
In the same dispatch the Secretary of State affirms that—
Since 1837 the United States have regarded Texas as an independent sovereignty as much as Mexico, and that trade and commerce with citizens of a government at war with Mexico can not on that account be regarded as an intercourse by which assistance and succor are given to Mexican rebels. The whole current of Mr. De Bocanegra's remarks runs in the same direction, as if the independence of Texas had not been acknowledged. It has been acknowledged; it was acknowledged in 1837 against the remonstrance and protest of Mexico, and most of the acts of any importance of which Mr. De Bocanegra complains flow necessarily from that recognition. He speaks of Texas as still being "an integral part of the territory of the Mexican Republic," but he can not but understand that the United States do not so regard it. The real complaint of Mexico, therefore, is in substance neither more nor less than a complaint against the recognition of Texan independence. It may be thought rather late to repeat that complaint, and not quite just to confine it to the United States to the exemption of England, France, and Belgium, unless the United States, having been the first to acknowledge the independence of Mexico herself, are to be blamed for setting an example for the recognition of that of Texas.
And he added that—
The Constitution, public treaties, and the laws oblige the President to regard Texas as an independent state, and its territory as no part of the territory of Mexico.
Texas had been an independent state, with an organized government, defying the power of Mexico to overthrow or reconquer her, for more than ten years before Mexico commenced the present war against the United States. Texas had given such evidence to the world of her ability to maintain her separate existence as an independent nation that she had been formally recognized as such not only by the United States, but by several of the principal powers of Europe. These powers had entered into treaties of amity, commerce, and navigation with her. They had received and accredited her ministers and other diplomatic agents at their respective courts, and they had commissioned ministers and diplomatic agents on their part to the Government of Texas. If Mexico, notwithstanding all this and her utter inability to subdue or reconquer Texas, still stubbornly refused to recognize her as an independent nation, she was none the less so on that account. Mexico herself had been recognized as an independent nation by the United States and by other powers many years before Spain, of which before her revolution she had been a colony, would agree to recognize her as such; and yet Mexico was at that time in the estimation of the civilized world, and in fact, none the less an independent power because Spain still claimed her as a colony. If Spain had continued until the present period to assert that Mexico was one of her colonies in rebellion against her, this would not have made her so or changed the fact of her independent existence. Texas at the period of her annexation to the United States bore the same relation to Mexico that Mexico had borne to Spain for many years before Spain acknowledged her independence, with this important difference, that before the annexation of Texas to the United States was consummated Mexico herself, by a formal act of her Government, had acknowledged the independence of Texas as a nation. It is true that in the act of recognition she prescribed a condition which she had no power or authority to impose—that Texas should not annex herself to any other power—but this could not detract in any degree from the recognition which Mexico then made of her actual independence. Upon this plain statement of facts, it is absurd for Mexico to allege as a pretext for commencing hostilities against the United States that Texas is still a part of her territory.
But there are those who, conceding all this to be true, assume the ground that the true western boundary of Texas is the Nueces instead of the Rio Grande, and that therefore in marching our Army to the east bank of the latter river we passed the Texan line and invaded the territory of Mexico. A simple statement of facts known to exist will conclusively refute such an assumption. Texas, as ceded to the United States by France in 1803, has been always claimed as extending west to the Rio Grande or Rio Bravo. This fact is established by the authority of our most eminent statesmen at a period when the question was as well, if not better, understood than it is at present. During Mr. Jefferson's Administration Messrs. Monroe and Pinckney, who had been sent on a special mission to Madrid, charged among other things with the adjustment of boundary between the two countries, in a note addressed to the Spanish minister of foreign affairs under date of the 28th of January, 1805, assert that the boundaries of Louisiana, as ceded to the United States by France, "are the river Perdido on the east and the river Bravo on the west," and they add that "the facts and principles which justify this conclusion are so satisfactory to our Government as to convince it that the United States have not a better right to the island of New Orleans under the cession referred to than they have to the whole district of territory which is above described." Down to the conclusion of the Florida treaty, in February, 1819, by which this territory was ceded to Spain, the United States asserted and maintained their territorial rights to this extent. In the month of June, 1818, during Mr. Monroe's Administration, information having been received that a number of foreign adventurers had landed at Galveston with the avowed purpose of forming a settlement in that vicinity, a special messenger was dispatched by the Government of the United States with instructions from the Secretary of State to warn them to desist, should they be found there, "or any other place north of the Rio Bravo, and within the territory claimed by the United States." He was instructed, should they be found in the country north of that river, to make known to them "the surprise with which the President has seen possession thus taken, without authority from the United States, of a place within their territorial limits, and upon which no lawful settlement can be made without their sanction." He was instructed to call upon them to "avow under what national authority they profess to act," and to give them due warning "that the place is within the United States, who will suffer no permanent settlement to be made there under any authority other than their own." As late as the 8th of July, 1842, the Secretary of State of the United States, in a note addressed to our minister in Mexico, maintains that by the Florida treaty of 1819 the territory as far west as the Rio Grande was confirmed to Spain. In that note he states that—
By the treaty of the 22d of February, 1819, between the United States and Spain, the Sabine was adopted as the line of boundary between the two powers. Up to that period no considerable colonization had been effected in Texas; but the territory between the Sabine and the Rio Grande being confirmed to Spain by the treaty, applications were made to that power for grants of land, and such grants or permissions of settlement were in fact made by the Spanish authorities in favor of citizens of the United States proposing to emigrate to Texas in numerous families before the declaration of independence by Mexico.
The Texas which was ceded to Spain by the Florida treaty of 1819 embraced all the country now claimed by the State of Texas between the Nueces and the Rio Grande. The Republic of Texas always claimed this river as her western boundary, and in her treaty made with Santa Anna in May, 1836, he recognized it as such. By the constitution which Texas adopted in March, 1836, senatorial and representative districts were organized extending west of the Nueces. The Congress of Texas on the 19th of December, 1836, passed "An act to define the boundaries of the Republic of Texas," in which they declared the Rio Grande from its mouth to its source to be their boundary, and by the said act they extended their "civil and political jurisdiction" over the country up to that boundary. During a period of more than nine years which intervened between the adoption of her constitution and her annexation as one of the States of our Union Texas asserted and exercised many acts of sovereignty and jurisdiction over the territory and inhabitants west of the Nueces. She organized and defined the limits of counties extending to the Rio Grande; she established courts of justice and extended her judicial system over the territory; she established a custom-house and collected duties, and also post-offices and post-roads, in it; she established a land office and issued numerous grants for land within its limits; a senator and a representative residing in it were elected to the Congress of the Republic and served as such before the act of annexation took place. In both the Congress and convention of Texas which gave their assent to the terms of annexation to the United States proposed by our Congress were representatives residing west of the Nueces, who took part in the act of annexation itself. This was the Texas which by the act of our Congress of the 29th of December, 1845, was admitted as one of the States of our Union. That the Congress of the United States understood the State of Texas which they admitted into the Union to extend beyond the Nueces is apparent from the fact that on the 31st of December, 1845, only two days after the act of admission, they passed a law "to establish a collection district in the State of Texas," by which they created a port of delivery at Corpus Christi, situated west of the Nueces, and being the same point at which the Texas custom-house under the laws of that Republic had been located, and directed that a surveyor to collect the revenue should be appointed for that port by the President, by and with the advice and consent of the Senate. A surveyor was accordingly nominated, and confirmed by the Senate, and has been ever since in the performance of his duties. All these acts of the Republic of Texas and of our Congress preceded the orders for the advance of our Army to the east bank of the Rio Grande. Subsequently Congress passed an act "establishing certain post routes" extending west of the Nueces. The country west of that river now constitutes a part of one of the Congressional districts of Texas and is represented in the House of Representatives. The Senators from that State were chosen by a legislature in which the country west of that river was represented. In view of all these facts it is difficult to conceive upon what ground it can be maintained that in occupying the country west of the Nueces with our Army, with a view solely to its security and defense, we invaded the territory of Mexico. But it would have been still more difficult to justify the Executive, whose duty it is to see that the laws be faithfully executed, if in the face of all these proceedings, both of the Congress of Texas and of the United States, he had assumed the responsibility of yielding up the territory west of the Nueces to Mexico or of refusing to protect and defend this territory and its inhabitants, including Corpus Christi as well as the remainder of Texas, against the threatened Mexican invasion.
But Mexico herself has never placed the war which she has waged upon the ground that our Army occupied the intermediate territory between the Nueces and the Rio Grande. Her refuted pretension that Texas was not in fact an independent state, but a rebellious province, was obstinately persevered in, and her avowed purpose in commencing a war with the United States was to reconquer Texas and to restore Mexican authority over the whole territory—not to the Nueces only, but to the Sabine. In view of the proclaimed menaces of Mexico to this effect, I deemed it my duty, as a measure of precaution and defense, to order our Army to occupy a position on our frontier as a military post, from which our troops could best resist and repel any attempted invasion which Mexico might make. Our Army had occupied a position at Corpus Christi, west of the Nueces, as early as August, 1845, without complaint from any quarter. Had the Nueces been regarded as the true western boundary of Texas, that boundary had been passed by our Army many months before it advanced to the eastern bank of the Rio Grande. In my annual message of December last I informed Congress that upon the invitation of both the Congress and convention of Texas I had deemed it proper to order a strong squadron to the coasts of Mexico and to concentrate an efficient military force on the western frontier of Texas to protect and defend the inhabitants against the menaced invasion of Mexico. In that message I informed Congress that the moment the terms of annexation offered by the United States were accepted by Texas the latter became so far a part of our own country as to make it our duty to afford such protection and defense, and that for that purpose our squadron had been ordered to the Gulf and our Army to take a "position between the Nueces and the Del Norte" or Rio Grande and to "repel any invasion of the Texan territory which might be attempted by the Mexican forces."