I first discovered Peter Connolly as a child. I loved reading about Greek and Roman history, and here were a series of books that talked about their military history. Also the books had amazing artwork by the author that really brought the text to life. Re-reading the books now in the one volume collected edition I find that they are just as good as I remember.
Greece and Rome at War is by Peter Connolly a respected historian who also happens to be an amazing illustrator, and this second talent is what really sells the book. The book begins with the Greek army and talks about hoplites and phalanxs and how Greek military tactics developed. Next is the Roman Republic and its wars with the Carthaginians led famously in the Second Punic War by Hannibal. Finally Connolly discusses the Roman Empire and the role of the legionary. Accompanying these histories are the authors paintings of armour, weapons and maps of battles as well as paintings of various soldiers in their battle gear.
Overall this is a great read. You can marvel at the artwork while learning a lot about the armies of the various time periods described. This book also makes a great reference tool for wargamers trying to get a feel foe the period, or looking for ideas on how to paint their models.
Here's an example of a painting by Connolly showing Greek Hoplites in battle.