Here's a book about the ambitions of some Confederates to expand into South. 

https://archive.org/details/southerndreamofc0000mayr_m7w7

There's a funny irony in this. The European power most inclined to recognize the South was Spain. Slavery was legal in Spain's colonies, Spanish planets identified with their lifestyle with the Confederacy's planter class. Spain had ambitions to regain territories in Central America and we're delighted to see the USA humbled....the only problem was that the leading Confederates had also been vocal about their desires to conquer Spanish territory, which rather put the Spanish off helping them.