Fort Pulaski was designed to defend the city of Savannah from attack by the sea. Considered invincible and 'strong as the Rocky Mountains', it's 7-10 ft thick brick walls were quickly decimated by new experimental rifled bore cannons. When the south aboandoned Tybee Island, it gave the Federal troops the position needed to bring the garrison's leader Gen Olmstead, to surrender in 48 hours.
The narrow wooded isolation room where prisoners were kept had an eerie feeling to it. I've seen it before on a ghost hunter show. Not one to believe in that stuff, I'm sure the conditions here were terrible.