Thucydides on A2/AD

Anti-access/area denial (A2/AD) is a modern concept with an ancient pedigree. In his History, Thucydides explained how Athens developed an A2/AD strategy based on asymmetric capabilities that contributed to the outbreak of the Peloponnesian War. After the Persian Wars, Athens built a series of walls and invested heavily in its navy, while Sparta maintained its traditional strength in land forces. Under the leadership of Pericles, Athens combined its walls and its navy into an integrated system for denying freedom of access and maneuver within the Aegean operational area, which became a critical factor in the outbreak of war.