Aelianus Tacticus () (fl. second century AD), also known as Aelian, was a Greek military writer who lived in Rome. Aelian's military treatise in fifty-three chapters on the tactics of the Greeks, titled On tactical arrays of the Greeks (), is dedicated to the Emperor Hadrian, though this is probably a mistake for Trajan, and the date 106 AD has been assigned to it. It is a handbook of Greek, i.e. Macedonian, drill and tactics as practiced by the Hellenistic successors of Alexander the Great. The author claims to have consulted all the best authorities, the most important of which was a lost treatise on the subject by Polybius. Perhaps the chief value of Aelian's work lies in his critical account of preceding works on the art of war, and in the fullness of his technical details in matters o