ar that followed Cannae was fundamentally different from the war as it had been fought in its first two years, from the fall of 218 when Hannibal descended into Italy until Cannae in the summer of 217. Although the succeeding phase, a war of maneuver, was foreshadowed by the strategy followed by Fabius during his dictatorship (and for a few months thereafter), the two opening years of the war were characterized by battles, the two set-piece battles of Trebia and Cannae, and the enormous ambush at Lake Trasumennus. Even in the last, though the Romans never had a chance there to deploy into battle order, the ambush was set up by Flaminius' determination to bring Hannibal to battle.
After Cannae, there were no further regular set-piece battles between Hannibal and the Romans on an equivalent scale, or with such decisive results, until Zama fully sixteen years later. The Romans avoided full-scale engagements in the field through much of that period, initially because after Cannae they had no army to fight one, and subsequently because they had learned by the hardest experience that fighting a battle against Hannibal was tantamount to being defeated by him. Thus the entire nature of the war changed with Cannae, becoming a complex series of marches and countermarches, not often and never decisively punctuated by direct confrontations between the armies.
Thus, before proceeding to the Roman response, and Hannibal's, to the new situation that arose after Cannae, it may be in order to look back at Cannae itself, and in the previous set-piece battle of Trebia, for the insights they offer into the nature of combat in the Second Roman War. As discussed in an earlier chapter, the traditional approach to military history, as followed by most historians from classical antiquity up until very recently, was a broad-brush one, dealing with the sweeping movements of entire forces, while taking what might be called micro-tactics--what actual...