Strong circumstantial evidence supporting piracy as a cause of the Civil War.

[Solvedit]

What you are saying is that mybe a couple of hundred pirates that moved into the Southern United States were any influence at all in the cause of the Civil War. I just don't see it.

There may have been more of them than that.  

Suppose some of them had learned to operate like a protection racket where they simply "skim off the cream without breaking the bottle."  

Besides that, there may have been a human trafficking culture. 

Then there were the people they supported.  

Their sudden absence could have caused an economic collapse in their host country.