Background: Over 2000 years ago during the Second Punic War the Carthaginian general Hannibal crossed the Alps and invaded Italy, inflicting a series of major defeats on the Romans, culminating in the battle of Cannae. They regarded it as their worst military disaster with 45 - 50.000 Roman foot soldiers and cavalry killed in one day.
Daly essentially uses Polybius' account since it is "The earliest extant account of the battle, it is clear, straightforward, and devoid of fanciful details." There are problems, but he is careful to use other evidence where it might apply.
The Carthaginians were outnumbered (about 42.000 to 86.000) but had greater experience and an advantage in mounted troops. The defeat of the Roman cavalry exposed the weak conscript troops in the flanks of the legions. A slow staged withdrawal by Hannibal's centre line concentrated his enemy while his strongest (Libyan) troops, engaged both flanks of the Roman army and drove it in from both sides. His cavalry returned to attack the Roman rear turning confusion into rout.
It's interesting to recreate the Carthaginian and Roman strategic decisions at this distance in time. ( )

No one who's interested in the ancient world or in military history can have gone without reading something about Hannibal's war against Rome. This book re-examines the battle of Cannae, where about 50,000 Romans and their allies were slaughtered in a morning. That's in the same ballpark as the dead at Nagasaki 60 years ago, or the American dead in Vietnam War.
Daly spends a lot of his time looking at equipment, tactics, leadership, in an attempt to discover (despite Polybius' lack of attention) exactly what is likely to have gone on during the battle.
He follows with an examination of how the battle is reported to have gone, teasing out some realistic/reasonable alternatives in interpretation. ( )