A. Richmond isn't a harbor town. Hence, no similarity.
Richmond is on the James River and in 1860 was accessable to the sea. In 1859-60, Richmond actually was the 7th busiest port out of the top 11 southern ports in terms of tariffs collected. Besides, your original post called Charleston the confederacy's biggest harbor. It was, in fact, second in terms of tariffs collected and fifth in terms of exports.
Castro didn't have the guts or means to drive out the United States. The Confederacy did have the means, and they USED THEM.
But if Castro did have the guts and means you would be out there cheering him on, right? After all, he would be in the right, according to your standards.
Close, but no cigar. The south lost at Antietam. Recognition didn't happen. The confederacy went on to their inevitable defeat.