The Grand Strategy of the Roman Empire: From the First Century A.D. to the… (original 1976; edition 1979)

While it's probably not a good book to start with if you know nothing of the Roman Empire and it's Army, this is a interesting book. Luttwak examines the strategy of the Empire in a modern way, looking at how Rome achieved a economy of force while trying to protect it's citizens/subjects from outside forces that would impact taxes. ( )