Abstract
This article examines how Greek and Roman military manuals codified deception and the concealment of information as a central element of warfare. Authors, including Xenophon, Aeneas Tacticus, Frontinus and Polyaenus, provide systematic instructions for hiding messages, exploiting perception, and securing communication. From steganography and signalling systems to inventive devices such as water clocks and astragali, these manuals show that concealment was not ad hoc but operationally essential. By focusing on prescriptive texts rather than narrative histories, the study highlights the practical sophistication of ancient military strategy and the enduring cross-cultural continuity of information as a decisive resource in warfare.