The conniving British, with their French allies, would turn Cuba into an emancipated hell from which they could interrupt American shipping and destabilize slavery in the South. They proved it with their involvement in Soulé’s duel. They showed it in their longstanding abolitionist foreign policy. They further demonstrated as much in their firm adherence to protecting Spain’s ownership of the island. Furthermore, they had tried the same scheme before with Texas. The Spanish, likewise, proved quite willing to let the British do it and embraced potential emancipation as one of their main weapons against American filibustering.
On the American side, a president who openly advocated for expansion sat in the White House. He had close dealings with filibuster John A. Quitman. He stacked his Cabinet with men who supported expansion at the expense of Mexico and Spain. He had just, via James Gadsden, cut a deal to get still more of Mexico added to the United States. He sent another devoted Cuba annexationist off to Madrid to represent the nation and connive to get the island. In every way, the administration seemed primed to make a move.
The Black Warrior affair gave Franklin Pierce his opening. The Louisiana legislature and John Slidell suggested a method: free Quitman from fear of prosecution and let him go take the island. The filibuster could neatly slip through the web of international entanglements. He and his private band had an open invitation from Cuban exiles and, despite their close ties to the administration did not serve it in any official role. Pierce could have told the world that he had no responsibility for the actions of independent Americans abroad. If the then-independent Cuba wanted to join the Union, that matter concerned only the United States and Cuba. If the British and French might object, and they had before, they would confine themselves to rhetorical complaints while their war with Russia raged and find the island securely in American hands before they had the ships and men free to contest it.
With all the stars so aligned, how on Earth did Cuba not fall right into American hands? The press had cooled on Cuba since the heady days of January, but wars would sell papers. James K. Polk engineered a profoundly controversial war with Mexico and enough of the nation fell in line, even if dealing with the spoils of his war gravely strained the Union. Antislavery men objected then, as they did now. If they had more of a movement behind them, Pierce had proved able to deploy Democratic party discipline and patronage against them over Kansas-Nebraska and that crisis touched far more deeply on the domestic concerns of the white North than a tropical island with its future already decided.
Yet American forces did not set foot uninvited and unwelcome on Cuba until June, 1898. What happened? We don’t know for sure, but already in April Marcy sent Soulé new instructions to try buying Cuba rather than waiting for Quitman to steal it. By that point, the Kansas-Nebraska Act had cleared the Senate but still faced the harder battle in the House. If the South could all unite behind securing Missouri’s slavery on its exposed western side, it might not have the same will to defend filibusters who wanted to bring in not just new slave territory, but territory largely spoken for and which could depress the value of American slaves and compete with its higher yields under the protection of American tariffs. Furthermore, filibustering had a whiff of disrepute about it. Would Quitman prove a loyal American or would he decide that he preferred to make himself king of Cuba?
If Cuba’s overthrow did result in a war with, Spain if not with Great Britain or France, the United States would need a competent navy to wage that war. In the spring of 1854, the United States Navy had exactly one top of the line warship. That ship stood ready for any eventuality…in East Asian waters. It found itself there as part of Commodore Perry’s force that convinced the Japanese, at gunpoint, to open their ports. It would be no help in any Caribbean war and, unlike in 1898, Washington lacked even the means to swiftly dispatch orders for it to attack the Spanish Philippines.
With all of these concerns, the fact that Caleb Cushing and Jefferson Davis often dominated Pierce did not quite hold in the face of a divided Cabinet. Cushing wanted Cuba badly, to the point of war, but Pierce’s Secretary of State, William L. Marcy, did not. With the Kansas-Nebraska fight still raging, Pierce reserved his political capital for the domestic struggle. Soulé got his new instructions and Pierce sent out a proclamation avowing that he would zealously enforce the Neutrality Laws against any ambitious filibusters. Absent the domestic battle over slavery in Kansas, his decision might very plausibly have gone the other way.