The Ostend Manifesto threatened war, which it treated as an inevitability unless Spain sold Cuba, against Spain, against its European allies, and against essentially the whole world. America would take on all comers to secure Cuba for its god, for its freedom, and for its slavery. No human power could stop the United States from intervening in a coming Cuban revolution. Fiery words, however, need not carry sudden violence in their wake. Diplomatic saber-rattling, like Soulé’s off-script forty-eight hour ultimatum to Spain in the Black Warrior affair, could arise from genuine feeling and national interest or from the need for a bit of domestic or international theater. The Manifesto’s text does not alone permit us to tell what category it falls into, but it at least provides rhetorical support for the seriousness of the threat.
Self-preservation is the law of 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.
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.
Spanish Cuba presented an existential crisis to the United States. National survival, on top of the survival of the white race in the South, depended on having Cuba. If Spain would not sell for the incredibly generous price offered
then, by every law, human and 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 our actually to consume the fair fabric of our Union.
Buchanan, Mason, and Soulé concluded with the ominous note that already the United States and Spain stood on that precipice. The Black Warrior affair very nearly brought them over the edge. If Soulé had his way, it would have. Spain stood unrepentant, secure in its legal rights. Only by selling the island could Spain avert an eventual war over Cuba.
So much for the hope that cautious old Buchanan would reign in fiery Soulé. Apparently, in the words of the Manifesto:
the present is an age of adventure, in which restless and daring spirits abound in every portion of the world.