This is part of the despatch which communicates to Mexico the fact of the conclusion of the treaty of annexation—that treaty, the conclusion of which the formal and reiterated declarations of the Mexican government informed our administration, during its negotiation, would be war. I will quote one of these declarations, the last one made by General Almonte, the Mexican minister, and in reply to the letter of our Secretary who considered the previous declarations as threats. General Almonte disclaims the idea of a threat—repeats his asseveration that it is a notice only, and that in a case in which it was the right and the duty of Mexico to give the notice which would apprise us of the consequences of carrying the treaty of annexation to a conclusion.

After receiving this notification from the Mexican minister, the letter of our present Secretary, of the 19th instant, just quoted, directing our chargé to inform the Mexican government of the conclusion of the treaty of annexation, must be considered as an official notification to Mexico that the war has begun! and so indeed it has! and as much to our astonishment as to that of the Mexicans! Who among us can ever forget the sensations produced in this chamber, on Wednesday last, when the marching and the sailing orders were read! and still more, when the message was read which had set the army and navy in motion!

These orders and the message, after having been read in this chamber, were sent to the printer, and have not yet returned: I can only refer to them as I heard them read, and from a brief extract which I took of the message; and must refer to others to do them justice. From all that I could hear, the war is begun; and begun by orders issued by the President before the treaty was communicated to the Senate! We are informed of a squadron, and an army of "observation," sent to the Mexican ports, and Mexican frontier, with orders to watch, remonstrate, and report; and to communicate with President Houston! Now, what is an army of observation, but an army in the field for war? It is an army whose name is known, and whose character is defined, and which is incident to war alone. It is to watch the ENEMY! and can never be made to watch a FRIEND! Friends cannot be watched by armed men, either individually or nationally, without open enmity. Let an armed man take a position before your door, show himself to your family, watch your movements, and remonstrate with you, and report upon you, if he judged your movements equivocal: let him do this, and what is it but an act of hostility and of outrage which every feeling of the heart, and every law of God and man, require you to resent and repulse? This would be the case with the mere individual; still more with nations, and when squadrons and armies are the watchers and remonstrants. Let Great Britain send an army and navy to lie in wait upon our frontiers, and before our cities, and then see what a cry of war would be raised in our country. The same of Mexico. She must feel herself outraged and attacked; she must feel our treaties broken; all our citizens within her dominions alien enemies; their commerce to be instantly ruined, and themselves expelled from the country. This must be our condition, unless the Senate (or Congress) saves the country. We are at war with Mexico now; and the message which covers the marching and sailing orders is still more extraordinary than they. The message assumes the republic of Texas to be part of the American Union by the mere signature of the treaty, and to remain so until the treaty is rejected, if rejected at all; and, in the mean time, the President is to use the army and the navy to protect the acquired country from invasion, like any part of the existing Union, and to treat as hostile all adverse possessors or intruders. According to this, besides what may happen at Vera Cruz, Tampico, Matamoros, and other ports, and besides what may happen on the frontiers of Texas proper, the Mexican population in New Mexico, and Governor Armijo, or in his absence the governor ad interim, Don Mariano Chaves, may find themselves pursued as rebels and traitors to the United States.

The war with Mexico, and its unconstitutionality, is fully shown: its injustice remains to be exhibited, and that is an easy task. What is done in violation of treaties, in violation of neutrality, in violation of an armistice, must be unjust. All this occurs in this case, and a great deal more. Mexico is our neighbor. We are at peace with her. Social, commercial, and diplomatic relations subsist between us, and the interest of the two nations requires these relations to continue. We want a country which was once ours, but which, by treaty, we have acknowledged to be hers. That country has revolted. Thus far it has made good its revolt, and not a doubt rests upon my mind that she will make it good for ever. But the contest is not over. An armistice, duly proclaimed, and not revoked, strictly observed by each in not firing a gun, though inoperative thus far in the appointment of commissioners to treat for peace: this armistice, only determinable upon notice, suspends the war. Two thousand miles of Texian frontier is held in the hands of Mexico, and all attempts to conquer that frontier have signally failed: witness the disastrous expeditions to Mier and to Santa Fé. We acknowledge the right—the moral and political right—of Mexico to resubjugate this province, if she can. We declare our neutrality: we profess friendship: we proclaim our respect for Mexico. In the midst of all this, we make a treaty with Texas for transferring herself to the United States, and that without saying a word to Mexico, while receiving notice from her that such transfer would be war. Mexico is treated as a nullity; and the province she is endeavoring to reconquer is suddenly, by the magic of a treaty signature, changed into United States domain. We want the country; but instead of applying to Mexico, and obtaining her consent to the purchase, or waiting a few months for the events which would supersede the necessity of Mexican consent—instead of this plain and direct course, a secret negotiation was entered into with Texas, in total contempt of the acknowledged rights of Mexico, and without saying a word to her until all was over. Then a messenger is despatched in furious haste to this same Mexico, the bearer of volunteer apologies, of deprecatory excuses, and of an offer of ten millions of dollars for Mexican acquiescence in what Texas has done. Forty days are allowed for the return of the messenger; and the question is, will he bring back the consent? That question is answered in the Mexican official notice of war, if the treaty of annexation was made! and it is answered in the fact of not applying to her for her consent before the treaty was made. The wrong to Mexico is confessed in the fact of sending this messenger, and in the terms of the letter of which he was the bearer. That letter of Mr. Secretary Calhoun, of the 19th of April, to Mr. Benjamin Green, the United States chargé in Mexico, is the most unfortunate in the annals of human diplomacy! By the fairest implications, it admits insult and injury to Mexico, and violation of her territorial boundaries! it admits that we should have had her previous consent—should have had her concurrence—that we have injured her as little as possible—and that we did all this in full view of all possible consequences! that is to say, in full view of war! in plain English, that we have wronged her, and will fight her for it. As an excuse for all this, the imaginary designs of a third power, which designs are four times solemnly disavowed, are brought forward as a justification of our conduct; and an incomprehensible terror of immediate destruction is alleged as the cause of not applying to her for her "previous consent" during the eight months that the negotiation continued, and during the whole of which time we had a minister in Mexico, and Mexico had a minister in Washington. This letter is surely the most unfortunate in the history of human diplomacy. It admits the wrong, and tenders war. It is a confession throughout, by the fairest implication, of injustice to Mexico. It is a confession that her "concurrence" and "her previous consent" were necessary.

It is now my purpose, Mr. President, to show that all this movement, which is involving such great and serious consequences, and drawing upon us the eyes of the civilized world, is bottomed upon a weak and groundless pretext, discreditable to our government, and insulting and injurious to Great Britain. We want Texas—that is to say, the Texas of La Salle; and we want it for great national reasons, obvious as day, and permanent as nature. We want it because it is geographically appurtenant to our division of North America, essential to our political, commercial, and social system, and because it would be detrimental and injurious to us to have it fall into the hands or to sink under the domination of any foreign power. For these reasons, I was against sacrificing the country when it was thrown away—and thrown away by those who are now so suddenly possessed of a fury to get it back. For these reasons, I am for getting it back whenever it can be done with peace and honor, or even at the price of just war against any intrusive European power: but I am against all disguise and artifice—against all pretexts—and especially against weak and groundless pretexts, discreditable to ourselves, offensive to others, too thin and shallow not to be seen through by every beholder, and merely invented to cover unworthy purposes. I am against the inventions which have been brought forward to justify the secret concoction of this treaty, and its sudden explosion upon us, like a ripened plot, and a charged bomb, forty days before the conventional nomination of a presidential candidate. In looking into this pretext, I shall be governed by the evidence alone which I find upon the face of the papers, regretting that the resolution which I have laid upon the table for the examination of persons at the bar of the Senate, has not yet been adopted. That resolution is in these words:

"Resolved, That the AUTHOR of the 'private letter' from London, in the summer of 1843 (believed to be Mr. Duff Green), addressed to the American Secretary of State (Mr. Upshur), and giving him the first intelligence of the (imputed) British anti-slavery designs upon Texas, and the contents of which 'private letter' were made the basis of the Secretary's leading despatch of the 8th of August following, to our chargé in Texas, for procuring the annexation of Texas to the United States, be SUMMONED to appear at the bar of the Senate, to answer on oath to all questions in relation to the contents of said 'private letter,' and of any others in relation to the same subject: and also to answer all questions, so far as he shall be able, in relation to the origin and objects of the treaty for the annexation of Texas, and of all the designs, influences, and interests which led to the formation thereof.

"Resolved, also, That the Senate will examine at its bar, or through a committee, such other persons as shall be deemed proper in relation to their knowledge of any, or all, of the foregoing points of inquiry."

I hope, Mr. President, this resolution will be adopted. It is due to the gravity of the occasion that we should have facts and good evidence before us. We are engaged in a transaction which concerns the peace and the honor of the country; and extracts from private letters, and letters themselves, with or without name, and, it may be, from mistaken or interested persons, are not the evidence on which we should proceed. Dr. Franklin was examined at the bar of the British House of Commons before the American war, and I see no reason why those who wish to inform the Senate, and others from whom the Senate could obtain information, should not be examined at our bar, or at that of the House, before the Senate or Congress engages in the Mexican war. It would be a curious incident in the Texas drama if it should turn out to be a fact that the whole annexation scheme was organized before the reason for it was discovered in London! and if, from the beginning, the abolition plot was to be burst upon us, under a sudden and overwhelming sense of national destruction, exactly forty days before the national convention at Baltimore! I know nothing about these secrets; but, being called upon to act, and to give a vote which may be big with momentous consequences, I have a right to know the truth; and shall continue to ask for it, until fully obtained, or finally denied. I know not what the proof will be, if the examination is had. I pretend to no private knowledge; but I have my impressions; and if they are erroneous, let them be effaced—if correct, let them be confirmed.

In the absence of the evidence which this responsible and satisfactory examination might furnish, I limit myself to the information which appears upon the face of the papers—imperfect, defective, disjointed, and fixed up for the occasion, as those papers evidently are. And here I must remark upon the absence of all the customary information which sheds light upon the origin, progress, and conclusion of treaties. No minutes of conferences—no protocols—no propositions, or counter-propositions—no inside view of the nascent and progressive negotiation. To supply all this omission, the Senate is driven to the tedious process of calling on the President, day by day, for some new piece of information; and the endless necessity for these calls—the manner in which they are answered—and the often delay in getting any answer at all—become new reasons for the adoption of my resolution, and for the examination of persons at the bar of the Senate.

The first piece of testimony I shall use in making good the position I have assumed, is the letter of Mr. Upshur, our Secretary of State, to Mr. Murphy, our chargé in Texas dated the 8th day of August, in the year 1843. It is the first one, so far as we are permitted to see, that begins the business of the Texas annexation; and has all the appearance of beginning it in the middle, so far as the United States are concerned, and upon grounds previously well considered: for this letter of the 8th of August, 1843, contains every reason on which the whole annexation movement has been defended, or justified. And, here, I must repeat what I have already said: in quoting these letters of the secretaries, I use the name of the writer to discriminate the writer, but not to impute it to him. The President is the author: the secretary only his head clerk, writing by his command, and having no authority to write any thing but as he commands. This important letter, the basis of all Texian "immediate" annexation, opens thus:

"Sir: A private letter from a citizen of Maryland, then in London, contains the following passage:

"'I learn from a source entitled to the fullest confidence, that there is now here a Mr. Andrews, deputed by the abolitionists of Texas to negotiate with the British government. That he has seen Lord Aberdeen, and submitted his project for the abolition of slavery in Texas, which is, that there shall be organized a company in England, who shall advance a sum sufficient to pay for the slaves now in Texas, and receive in payment Texas lands; that the sum thus advanced shall be paid over as an indemnity for the abolition of slavery; and I am authorized by the Texian minister to say to you, that Lord Aberdeen has agreed that the British government will guarantee the payment of the interest on this loan, upon condition that the Texian government will abolish slavery.'

"The writer professes to feel entire confidence in the accuracy of this information. He is a man of great intelligence, and well versed in public affairs. Hence I have every reason to confide in the correctness of his conclusions."