Pyrrhus invaded Italy at the start of the campaigning season in 280 BC. In two brutal and bloody battles he successfully defeated the Romans. The Greek king, though, having seen so many of his soldiers slaughtered in achieving this success, was said to have remarked, ‘With another victory like this, we will be finished!’ (Hence our modern phrase ‘pyrrhic victory’.)
Ancient Rome: The Rise and Fall of An Empire by Simon Baker
Ancient Rome: The Rise and Fall of An Empire is an excellent book for those interested in an introduction to the Roman Empire that goes further than you were taught in school, yet remains readable.