I have a copy of the Peter Connolly book, and it is a very good general source of information on Greek and Roman warfare (Nice illustrations too). It, actually, spends most of it's time concentrating on Rome and her wars with Carthage, and was obviously well re-searched at the time.
It was first published in 1981 and I believe Mr Connelly is a well respected historian. I would say it is the kind of work that gives you a good initial grounding in a subject before moving on to more extensive research, not something one treats as the only source!
Bookmarks