Technically Moultrie was a part of an ambush site of forts in Charleston Harbor. Go visit and get the story first hand and see for yourself. Ocean currents made the only approach to Charleston Harbor from the south. To enter Charleston Harbor you had to go bow first at Fort Moultrie which could shell you until you got turned and were able to shoot back. At which time you got it broadsides from Moultrie on your right and Sumter on your left. Then if you made it past the entrance you had to deal with East Battery on the mainland. They didn't build military installations for looks back then.