Fort Sumter is a historical sea fort in Charleston, South Carolina. It appeared in Season Three episode "The Red Badge of Gayness".
Background
As a tour guide was leading a group of tourists in Fort Sumter, he invited the tourists to imagine themselves back in the Civil War as a Unionist soldier when they were surrounded by thousands of Confederate soldiers, only to face the exit and witness what he had exactly described. The drunk Confederate re-enactors charged forward and took control of the fort without resistance. Although the U.S. National Guard tried to deal with the re-enactors, while preparing to destroy the fort, the entire South Carolina Confederates had arrived in time, outnumbering the National Guard. Eric Cartman (as Robert E. Lee) then decided to rally his army and march into Washington D.C.