Jan Fischer, American Soldier In His Military Life

The Classical Greeks and the Romans wrote prolifically on military campaigning. Among the best-known Roman works are Julius Caesar's commentaries on the Gallic Wars and the Roman Civil war - written about 50 BC.
Two major works on tactics come from the late Roman period: Taktike Theoria by Aelianus Tacticus and De Re Militari ("On military matters") by Vegetius. Taktike Theoria examined Greek military tactics, and was most influential in the Byzantine world and during the Golden Age of Islam.
De Re Militari formed the basis of European military tactics until the late 17th century. Perhaps its most enduring maxim is Igitur qui desiderat pacem, praeparet bellum (let he who desires peace prepare for war).
Due to the changing nature of combat with the introduction of artillery in the European Middle Ages, and infantry firearms in the Renaissance, attempts were made to define and identify those strategies, grand tactics and tactics that would produce a victory more often than that achieved by the Romans in praying to the gods before the battle.