It is often thought that antebellum Southern slave interests desired Cuban annexation, though Northern commercialism more actively promoted this acquisition. It is noteworthy that US Navy Lt. John Newland Maffitt, later a famed naval captain of the Confederacy, pursued and captured many New England slavers off Cuba in the late 1850's.
Bernhard Thuersam, Circa1865
Northern Commercial Interests Desire Cuba:
"The United States became especially dependent on shipments of Cuban sugar, for Louisiana plantations in the early nineteenth century could only accommodate about one-third of the national demand for the product. Not only did this trade contribute significantly to the commercial growth of New York City — which became a center for sentiment favoring the annexation of the island — but commercial interests all over the eastern United States were dependent on it.
Many Americans took it for granted that sooner or later the island would gravitate toward the United States . . . and perhaps lead to a more effective suppression of the slave trade, since Cuba was a key station in that traffic. Even in the 1850's, when the questions of slavery and Cuba became virtually inseparable, two Northern presidents — Franklin Pierce of New Hampshire and James Buchanan of Pennsylvania — made determine efforts to purchase Cuba from Spain.
In the late 1840s . . . pro-annexation elements were investigating a number of ways of getting Americans involved in their cause. [Venezuelan revolutionary] Narciso Lopez . . . emerged as [the Cuban exiles in America] leader . . . [and] Lopez's main body of troops was with him in New York. [Though Lopez's efforts failed], he had gained considerable support in New York City and elsewhere in the North. Northerners, as well as exiled Cubans and European revolutionary refugees, had made substantial contributions to his movements in terms of manpower and financing."
(The Southern Dream of a Caribbean Empire, Robert E. May, LSU Press, 1973, excerpts, pp. 16-30)