Louisiana had been the property of France, and by a secret contract between that country and Spain in 1762, as well as by treaties between France, Spain, and England, in the following year, the French dominion was extinguished on the continent of America. In consequence of the treaty between this country and England in 1783, the Mississippi became the western boundary of the United States, from its source to the thirty-first degree of north latitude, and thence, on the same parallel, to the St. Mary's. France, it will be remembered, had always claimed dominion in Louisiana to the Rio Bravo del Norte, or Rio Grande; by virtue:—
1st. Of the discovery of the Mississippi from near its source to the ocean.
2d. Of the possession taken, and establishment made by La Salle, at the bay of Saint Bernard, west of the river Trinity and Colorado, by authority of Louis XIV. in 1635—notwithstanding the subsequent destruction of the colony.
3d. Of the charter of Louis XIV. to Crozat in 1712.
4th. Of the historical authority of Du Pratz, Champigny and the Count de Vergennes.
5th. Of the authority of De Lisle's map, and of the map published in 1762, by Don Thomas Lopez, Geographer to the king of Spain, as well as of various other maps, atlases, and geographical authorities.
By an article of the secret treaty of San Ildefonso in October, 1800, Spain retroceded Louisiana to France, but this treaty was not promulgated until the beginning of 1802. The paragraph of cession is as follows: "His Catholic majesty engages to retrocede to the French republic, six months after the full and entire execution of the conditions and stipulations above recited, relative to his royal highness the Duke of Parma, the colony and province of Louisiana, with the same extent that it already has in the hands of Spain, and that it had when France possessed it, and, such as it should be, after the treaties passed subsequently between Spain and other powers." In 1803, Bonaparte, the first consul of the French republic, ceded Louisiana to the United States, as fully, and in the same manner, as it had been retroceded to France by Spain, under the treaty of San Ildefonso; and, by virtue of this grant, Messrs. Madison, Monroe, Adams, Clay, Van Buren, Jackson, and Polk, contended that the original limit of the new state had been the Rio Grande. However, by the third article of our treaty with Spain, in 1819, all our pretensions to extend the territory of Louisiana towards Mexico on the Rio Grande, were abandoned by adopting the river Sabine as our boundary in that quarter.
The Mexican authorities upon this subject are either silent or doubtful. No light is to be gathered from the geographical researches of Humboldt, whose elucidations of New Spain are in many respects the fullest and most satisfactory. In the year 1835, Stephen Austin published a map of Texas, representing the Nueces as the western confine,—and in 1836, General Almonte the former minister from Mexico to the United States, published a memoir upon Texas in which, whilst describing the Texan department of Bejar, he says—"That notwithstanding it has been hitherto believed that the Rio de las Nueces is the dividing line of Coahuila and Texas, inasmuch as it is always thus represented on maps, I am informed by the government of the state, that geographers have been in error upon this subject; and that the true line should commence at the mouth of the river Aransaso, and follow it to its source; thence, it should continue by a straight line until it strikes the junction of the rivers Medina and San Antonio, and then, pursuing the east bank of the Medina to its head waters, it should terminate on the confines of Chihuahua." [67]
The true origin of the Mexican war was not this march of Taylor and his troops from the Nueces to the Rio Grande, through the debatable land. The American and Mexican troops were brought face to face by the act, and hostilities were the natural result after the exciting annoyances upon the part of the Mexican government which followed the union of Texas with our confederacy. Besides this, General Paredes, the usurping president, had already declared in Mexico, on the 18th of April, 1846, in a letter addressed to the commanding officer on the northern frontier, that he supposed him at the head of a valiant army on the theatre of action;—and that it was indispensable to commence hostilities, the Mexicans themselves taking the initiative!
We believe that our nation and its rulers earnestly desired honorable peace, though they did not shun the alternative of war. It was impossible to permit a conterminous neighbor who owed us large sums of money, and was hostile to the newly adopted state, to select unopposed her mode and moment of attack. Mexico would neither resign her pretensions upon Texas, negotiate, receive our minister, nor remain at peace. She would neither declare war, nor cultivate friendship, and the result was, that when the armies approached each other, but little time was lost in resorting to the cannon and the sword.