The Golden Circle (Spanish: Círculo Dorado) was an unrealized 1850s proposal by the Knights of the Golden Circle to expand the number of slave states. It envisioned the annexation of several areas—Mexico, Central America, northern South America, Cuba, and the rest of the Caribbean—into the United States in order to vastly increase the number of slave states (it was proposed that Mexico alone be divided into 25 new slave states) and thus the power of the slave holding Southern upper classes. After the Dred Scott Decision (1857) increased anti-slavery agitation, it was advocated by the Knights of the Golden Circle that the Southern United States should secede in their own confederation and invade and annex the area of the golden circle to vastly expand the power of the South.
Wikipedia, from Woodward, Colin American Nations: A History of the Eleven Rival Regional Cultures of North America New York:2011 Penguin Page 207
“During this period directly following the Mexican War, Manifest Destiny became “Sectional Destiny,” with Southerners leading the fight for increased Caribbean possessions. May points out that it is remarkable that Cuba did not become a U.S. possession during these years; almost every president elected during this time period favored annexation and three attempted to outright buy the island from Spain. Furthermore, the Spanish gave Southerners the pretext they wanted in February, 1854 when the American steamer Black Hawk entered Havana Harbor with nine hundred bales of cotton on board. Spanish authorities seized the vessel on the pretext that it had not complied with harbor regulations. President Pierce could have used this as a pretext for war, or he could have endorsed the gathering filibustering expedition of John A. Quitman of Mississippi to seize the island.
John Quitman led the Cuba movement of 1854-55 to wrest the island from Spain. In 1850 Quitman felt the South should secede, but short of that, he viewed the annexation of Cuba as the next best thing to strengthen states rights in the Union. Quitman’s planned expedition elicited a great deal of excitement among Southerners; almost all the prominent Texans of the time, including John S. Ford, Hugh McLeod, John Marshall, James P. Henderson and Hiram Waller all endorsed the plan, as did U.S. Senator from Mississippi Jefferson Davis and President Pierce...
The next major filibustering expedition in the Caribbean came in 1856 when the native Tennessean William Walker raised an army and actually conquered and occupied Nicaragua for a short time...
Throughout the 1850s Southerners, especially Texans, advocated the annexation of Mexican territory as well. It seemed to them a logical outgrowth of the Manifest Destiny that had already added half of Mexico’s national territory to the U.S. in 1848. President James Buchanan especially pushed hard on a protectorate treaty, known as the Lane Treaty that reached the Senate for a vote in 1860. Of course, the treaty failed because of the opposition by the Republican Party, but Buchanan’s commitment to annexation did not end with Mexico.
In 1859 Buchanan authorized $30 million to purchase Cuba from Spain. Senator James Slidell of Louisiana sponsored the bill in the senate, and even though the bill went down to defeat in a highly charged political atmosphere, it illustrates the fact that James Buchanan aspired to every bit as much territorial acquisition as had President James K. Polk, the quintessential expansionist.
This expansionist tendency is not to say that some Southerners did not oppose expansion, because many, primarily South Carolinians, did just that. James Henry Hammond, John C. Calhoun and others opposed annexation on the grounds that it obscured other, more pressing matters of Southern rights within the Union. Calhoun also opposed the acquisition of Mexico because along with it would come millions of Mexicans.”
John R. Lundberg, Texas Christian University
http://personal.tcu.edu/swoodworth/May.htm