Berenike was a gateway to the distant lands of Africa and the Indian Ocean littoral and the archaeological record from the site testifies to the scope and rich array of goods passing through this Red Sea port. However, investigation of the Hellenistic origins of the town began in earnest only after a full magnetic survey was completed of the western fringes of the site where the Ptolemaic foundation was believed to have been established. Recent excavations in 2010 and 2012 have contributed important new data about the architecture of this part of the town. Of particular interest were the remains of a presumed tetrapyrgion associated with a huge defensive complex, roughly 150 m by 80 m in size, which may have been used, among other things, for bringing through wild elephants from Africa imported for use by the Ptolemaic army. This contribution initiates a series of articles by the author on the Hellenistic defenses now under excavation at Berenike, presenting an overview of the location and structure of the great fort/base of Berenike Trogodytika and its role in the network of military harbors on the Red Sea coast, and the posts on the routes and fortified outposts of the Eastern Desert.