SIR:--The undersigned, in compliance with the wish expressed by the President in the several confidential despatches you have addressed to us, respectively, to that effect, have met in conference, first at Ostend, in Belgium, on the 8th, 10th, and 11th instant, and then at Aix la Chapelle in Prussia, on the days next following, up to the date hereof.

There has been a full and unresolved interchange of views and sentiments between us, which we are most happy to inform you has resulted in a cordial coincidence of opinion on the grave and important subjects submitted to our consideration.

We have arrived at the conclusion, and are thoroughly convinced, that an immediate and earnest effort ought to be made by the government of the United States to purchase Cuba from Spain at any price for which it can be obtained, not exceeding the sum of .

[The three ministers then argue that Cuba is essential for US national security and make the amazing claim that the US assuming control from the Spanish would be to Spain's advantage. Here is the heart of the manifesto.]

The proposal should, in our opinion, be made in such a manner as to be presented through the necessary diplomatic forms to the Supreme Constituent Cortes about to assemble. On this momentous question, in which the people both of Spain and the United States are so deeply interested, all our proceedings ought to be open, frank, and public. They should be of such a character as to challenge the approbation of the world.

We firmly believe that, in the progress of human events, the time has arrived when the vital interests of Spain are as seriously involved in the sale, as those of the United States in the purchase, of the island and that the transaction will prove equally honorable to both nations.

Under these circumstances we cannot anticipate a failure, unless possibly through the malign influence of foreign powers who possess no right whatever to interfere in the matter.

We proceed to state some of the reasons which have brought us to this conclusion, and, for the sake of clearness, we shall specify them under two distinct heads:

I. The United States ought, if practicable, to purchase Cuba with as little delay as possible.

2. The probability is great that the government and Cortes of Spain will prove willing to sell it, because this would essentially promote the highest and best interests of the Spanish people.

Then, I. It must be clear to every reflecting mind that, from the peculiarity of its geographical position, and the considerations attendant on it, Cuba is as necessary to the North American republic as any of its present members, and that it belongs naturally to that great family of States of which the Union is the providential nursery.

From its locality it commands the mouth of the Mississippi and the immense and annually increasing trade which must seek this avenue to the ocean.

On the numerous navigable streams, measuring an aggregate course of some thirty thousand miles, which disembogue themselves through this magnificent river into the Gulf of Mexico, the increase of the population within the last ten years amounts to more than that of the entire Union at the time Louisiana was annexed to it.

The natural and main outlet to the products of this entire population, the highway of their direct intercourse with the Atlantic and the Pacific States, can never be secure, but must ever be endangered whilst Cuba is a dependency of a distant power in whose possession it has proved to be a source of constant annoyance and embarrassment to their interests.

Indeed, the Union can never enjoy repose, nor possess reliable security, as long as Cuba is not embraced within its boundaries.

Its immediate acquisition by our government is of paramount importance, and we cannot doubt but that it is a consummation devoutly wished for by its inhabitants.

The intercourse which its proximity to our coasts begets and encourages between them and the citizens of the United States, has, in the progress of time, so united their interests and blended their fortunes that they now look upon each other as if they were one people and had but one destiny.

Considerations exist which render delay in the acquisition of this island exceedingly dangerous to the United States.

The system of immigration and labor lately organized within its limits, and the tyranny and oppression which characterize its immediate rulers, threaten an insurrection at every moment which may result in direful consequences to the American people.

Cuba has thus become to us an unceasing danger, and a permanent cause of anxiety and alarm.

But we need not enlarge on these topics. It can scarcely be apprehended that foreign powers, in violation of international law, would interpose their influence with Spain to prevent our acquisition of the island. Its inhabitants are now suffering under the worst of all possible governments, that of absolute despotism, delegated by a distant power to irresponsible agents, who are changed at short intervals, and who are tempted to improve the brief opportunity thus afforded to accumulate fortunes by the basest means.

As long as this system shall endure, humanity may in vain demand the suppression of the African slave trade in the island. This is rendered impossible whilst that infamous traffic remains an irresistible temptation and a source of immense profit to needy and avaricious officials, who, to attain their ends, scruple not to trample the most sacred principles under foot. The Spanish government at home may be well disposed, but experience has proved that it cannot control these remote depositaries of its power.

Besides, the commercial nations of the world cannot fail to perceive and appreciate the great advantages which would result to their people from a dissolution of the forced and unnatural connexion between Spain and Cuba, and the annexation of the latter to the United States. The trade of England and France with Cuba would, in that event, assume at once an important and profitable character, and rapidly extend with the increasing population and prosperity of the island.

2. But if the United States and every commercial nation would be benefited by this transfer, the interests of Spain would also be greatly and essentially promoted.

She cannot but see what such a sum of money as we are willing to pay for the island would effect in the development of her vast natural resources.

Two-thirds of this sum, if employed in the construction of a system of railroads, would ultimately prove a source of greater wealth to the Spanish people than that opened to their vision by Cortez. Their prosperity would date from the ratification of that treaty of cession.

France has already constructed continuous lines of railways from Havre, Marseilles, Valenciennes, and Strasbourg, via Paris, to the Spanish frontier, and anxiously awaits the day when Spain shall find herself in a condition to extend these roads through her northern provinces to Madrid, Seville, Cadiz, Malaga, and the frontiers of Portugal.

This object once accomplished, Spain would become a centre of attraction for the traveling world, and secure a permanent and profitable market for her various productions. Her fields, under the stimulus given to industry by remunerating prices, would teem with cereal grain, and her vineyards would bring forth a vastly increased quantity of choice wines. Spain would speedily become, what a bountiful Providence intended she should be, one of the first nations of Continental Europe--rich, powerful, and contented.

Whilst two-thirds of the price of the island would be ample for the completion of her most important public improvements, she might, with the remaining forty millions, satisfy the demands now pressing so heavily upon her credit, and create a sinking fund which would gradually relieve her from the overwhelming debt now paralyzing her energies.

Such is her present wretched financial condition, that her best bonds are sold upon her own Bourse at about one-third of their par value; whilst another class, on which she pays no interest, have but a nominal value, and are quoted at about one-sixth of the amount for which they were issued.

Besides, these latter are held principally by British creditors who may, from day to day, obtain the effective interposition of their own government for the purpose of coercing payment. Intimations to that effect have been already thrown out from high quarters, and unless some new source of revenue shall enable Spain to provide for such exigencies, it is not improbable that they may be realized.

Should Spain reject the present golden opportunity for developing her resources, and removing her financial embarrassments, it may never again return.

Cuba, in its palmiest days, never yielded her exchequer after deducting the expenses of its government a clear annual income of more than a million and a half of dollars. These expenses have increased to such a degree as to leave a deficit chargeable on the treasury of Spain to the amount of six hundred thousand dollars.

In a pecuniary point of view, therefore, the island is an incumbrance, instead of a source of profit, to the mother country.

Under no probable circumstances can Cuba ever yield to Spain one per cent. on the large amount which the United States are willing to pay for its acquisition. But Spain is in imminent danger of losing Cuba, without remuneration.

Extreme oppression, it is now universally admitted, justifies any people in endeavoring to relieve themselves from the yoke of their oppressors. The sufferings which the corrupt, arbitrary, and unrelenting local administration necessarily entails upon the inhabitants of Cuba, cannot fail to stimulate and keep alive that spirit of resistance and revolution against Spain, which has, of late years, been so often manifested. In this condition of affairs it is vain to expect that the sympathies of the people of the United States will not be warmly enlisted in favor of their oppressed neighbors.

We know that the President is justly inflexible in his determination to execute the neutrality laws; but should the Cubans themselves rise in revolt against the oppression which they suffer, no human power could prevent citizens of the United States and liberal minded men of other countries from rushing to their assistance. Besides, the present is an age of adventure, in which restless and daring spirits abound in every portion of the world.

It is not improbable, therefore, that Cuba may be wrested from Spain by a successful revolution; and in that event she will lose both the island and the price which we are now willing to pay for it--a price far beyond what was ever paid by one people to another for any province.

It may also be remarked that the settlement of this vexed question, by the cession of Cuba to the United States, would forever prevent the dangerous complications between nations to which it may otherwise give birth.

It is certain that, should the Cubans themselves organize an insurrection against the Spanish government, and should other independent nations come to the aid of Spain in the contest, no human power could, in our opinion, prevent the people and government of the United States from taking part in such a civil war in support of their neighbors and friends.

But if Spain, dead to the voice of her own interest, and actuated by stubborn pride and a false sense of honor, should refuse to sell Cuba to the United States, then the question will arise, What ought to be the course of the American government under such circumstances? Self-preservation is the first law of nature, with States as well as with individuals. All nations have, at different periods, acted upon this maxim. Although it has been made the pretext for committing flagrant injustice, as in the partition of Poland and other similar cases which history records, yet the principle itself, though often abused, has always been recognized.

The United States have never acquired a foot of territory except by fair purchase, or, as in the case of Texas, upon the free and voluntary application of the people of that independent State, who desired to blend their destinies with our own.

Even our acquisitions from Mexico are no exception to this rule, because, although we might have claimed them by the right of conquest in a just war, yet we purchased them for what was then considered by both parties a full and ample equivalent.

Our past history forbids that we should acquire the island of Cuba without the consent of Spain, unless justified by the great law of self-preservation. We must, in any event, preserve our own conscious rectitude and our own self-respect.

Whilst pursuing this course we can afford to disregard the censures of the world, to which we have been so often and so unjustly exposed.

After we shall have offered Spain a price for Cuba far beyond its present value, and this shall have been refused, it will then be time to consider the question, does Cuba, in the possession of Spain, seriously endanger our internal peace and the existence of our cherished Union?

Should this question be answered in the affirmative, then, by every law, human und divine, we shall be justified in wresting it from Spain if we possess the power, and this upon the very same principle that would justify an individual in tearing down the burning house of his neighbor if there were no other means of preventing the flames from destroying his own home.

Under such circumstances we ought neither to count the cost nor regard the odds which Spain might enlist against us. We forbear to enter into the question, whether the present condition of the island would justify such a measure? We should, however, be recreant to our duty, be unworthy of our gallant forefathers, and commit base treason against our posterity, should we permit Cuba to be Africanized and become a second St. Domingo, with all its attendant horrors to the white race, and suffer the flames to extend to our own neighboring shores, seriously to endanger or actually to consume the fair fabric of our Union.

We fear that the course and current of events are rapidly tending towards such a catastrophe. We, however, hope for the best, though we ought certainly to be prepared for the worst.

We also forbear to investigate the present condition of the questions at issue between the United States and Spain. A long series of injuries to our people have been committed in Cuba by Spanish officials and are unredressed. But recently a most flagrant outrage on the rights of American citizens and on the flag of the United States was perpetrated in the harbor of Havana under circumstances which, without immediate redress, would have justified a resort to measures of war in vindication of national honor. That outrage is not only unatoned, but the Spanish government has deliberately sanctioned the acts of its subordinates and assumed the responsibility attaching to them.

Nothing could more impressively teach us the danger to which those peaceful relations it has ever been the policy of the United States to cherish with foreign nations are constantly exposed than the circumstances of that case. Situated as Spain and the United States are, the latter have forborne to resort to extreme measures.

But this course cannot, with due regard to their own dignity as an independent nation, continue; and our recommendations, now submitted, are dictated by the firm belief that the cession of Cuba to the United States, with stipulations as beneficial to Spain as those suggested, is the only effective mode of settling all past differences and of securing the two countries against future collisions.

We have already witnessed the happy results for both countries which followed a similar arrangement in regard to Florida.