The campaign classification established by the U.S. National Park Service, which calls these the Lower Seaboard Theater and Gulf Approach operations, is more fine-grained than the one used in this article. Some minor NPS campaigns have been omitted and some have been combined into larger categories. Only a few of the 31 battles the NPS classifies for this theater are described. The Port Royal Expedition of 1861 has been added, although it has not been classified by the NPS. Boxed text in the right margin show the NPS campaigns associated with each section.