It would seem to be the desire of the Mexican government to evade the redress of the real injuries of our citizens, by confining the negotiation to the adjustment of a pecuniary indemnity for its imaginary rights over Texas. This cannot be tolerated. The two subjects must proceed hand in hand. They can never be separated. It is evidently with the view of thus limiting the negotiation, that the Mexican authorities have been quibbling about the mere form of your credentials; without even asking whether you had instructions and full powers to adjust the Texan boundary. The advice of the Council of Government seems to have been dictated by the same spirit. They do not advise the Mexican government to refuse to receive you; but, assuming the fact that the government had agreed to receive a plenipotentiary to treat upon the subject of Texas alone, they infer that it is not bound to receive an envoy extraordinary and minister plenipotentiary without this limitation.
In the mean time, the President, in anticipation of the final refusal of the Mexican government to receive you, has ordered the army of Texas to advance and take a position on the left bank of the Rio Grande, and has directed that a strong fleet shall be immediately assembled in the Gulf of Mexico. He will thus be prepared to act with vigor and promptitude the moment that Congress shall give him the authority.
This despatch will not be transmitted to you by the Mississippi. That vessel will be detained at Pensacola for the purpose of conveying to you instructions with the least possible delay, after we shall have heard from you by the Porpoise; and of bringing you home in case this shall become necessary.
By your despatch No. 2, written at Vera Cruz, you ask for an explanation of my instructions relative to the claim of Texas on that portion of New Mexico east of the Del Norte; and you state the manner in which you propose to treat the subject in the absence of any such explanation. I need say nothing in relation to your inquiry; but merely to state that you have taken the proper view of the question, and that the course which you intend to pursue meets the approbation of the President.
I am, &c.,
James Buchanan.
It is now necessary to recur to the military movement referred to in this despatch. In August, 1845, General Zachary Taylor was encamped at Corpus Christi, in Texas, in command of a small American force of fifteen hundred troops. In the following November, his force was recruited to about four thousand men. On the 8th of March, 1846, acting under the President’s orders, given in anticipation of a refusal of the Mexican authorities to receive or to treat with Mr. Slidell, Taylor moved towards the Rio Grande, and on the 28th his little army reached the banks of that river, opposite the town of Matamoras. In a despatch written on the 12th of March to Mr. Slidell, Mr. Buchanan said:
It is not deemed necessary to modify the instructions which you have already received, except in a single particular; and this arises from the late revolution effected in the government of the Mexican Republic by General Paredes. I am directed by the President to instruct you not to leave that republic, until you shall have made a formal demand to be received by the new government. The government of Paredes came into existence not by a regular constitutional succession, but in consequence of a military revolution by which the subsisting constitutional authorities were subverted. It cannot be considered as a mere continuation of the government of Herrera. On the contrary, the form of government has been entirely changed, as well as all the high functionaries at the head of the administration. The two governments are certainly not so identical that the refusal of the one to receive you ought to be considered conclusive evidence that such would be the determination of the other. It would be difficult, on such a presumption, in regard to so feeble and distracted a country as Mexico, to satisfy the American people that all had been done which ought to have been done to avoid the necessity of resorting to hostilities.
On your return to the United States, energetic measures against Mexico would at once be recommended by the President; and these might fail to obtain the support of Congress, if it could be asserted that the existing government had not refused to receive our minister. It would not be a sufficient answer to such an allegation that the government of Herrera had refused to receive you, and that you were therefore justified in leaving the country after a short delay, because, in the meantime, the government of Paredes had not voluntarily offered to reverse the decision of his predecessor.
The President believes that, for the purpose of making this demand, you ought to return to the City of Mexico, if this be practicable, consistently with the national honor. It was prudent for you to leave it during the pendency of the late revolution, but this reason no longer continues. Under existing circumstances your presence there ought to be productive of the most beneficial consequences......