So, I took your advice and searched under "Robert Rhett". I came up with the below. Is this the same Robert Rhett you are referring to?
Proponents argued that the Golden Circle would bring together jurisdictions that depended on slavery. The Knights of the Golden Circle was the U.S. organization formed to promote and help create the Pan-American union of states. It was organized in 1854 by George W. L. Bickley, a Virginia-born doctor, editor, and adventurer living in Cincinnati, Ohio. Membership increased slowly until 1859 and reached its height in 1860. The membership, scattered from New York to California and into Latin America, was never large. Some Knights of the Golden Circle active in northern states, such as Illinois, were accused of anti-Union activities after the Civil War began. Robert Barnwell Rhett, called by some the "father of secession", said a few days after Lincoln's election: "We will expand, as our growth and civilization shall demand - over Mexico - over the isles of the sea - over the far-off Southern tropics - until we shall establish a great Confederation of Republics - the greatest, freest and most useful the world has ever seen."
Look here:
http://www.civilwarcauses.org/rhett.htm
It's the most famous thing he ever did. You had to walk right past it to get to the Golden Circle stuff, which you concede was the transactions of a scattering of very small groups and ultimately insignificant to the course of history.
Thanks for the link.
That is the connection I recall. I wasn't aware of the wider ideology and transnational ambitions.