definite obligation on Philip's part. Indeed, Polybius' text is more nearly a non-agression pact than a positive alliance. However, the fragment in Polybius is isolated, with no context; it may well be a subsequent agreement reached after Philip's intervention in the war came to nothing.
Returning to the alliance reported by Livy, it is difficult to imagine a more opportunistic arrangement from Philip's point of view. Indeed, since he was not even "inclined to the side of success" until after Cannae--Hannibal's two previous smashing victories notwithstanding--one is reminded of nothing so much as the Soviet declaration of war against Japan in the last few days of the Second World War, after the American atomic bombings. In the still-heady military and political environment of 215, Philip might well have hoped that Rome would collapse fairly quickly, in which case he would then have procured the services of Hannibal and his army with minimal effort on his own part.
Hannibal's reason for accepting these terms was doubtless more straightforward. He could be confident of victory over any Roman army that tried to face him. However, his resources were still being stretched very thin by the sort of war he was compelled to fight. He was attempting on the one hand to keep up the pressure on the Romans, while on the other hand answering calls for help from his Italian allies, whose own attempted military adventures, as recounted in the last chapter, more often than not only got them in trouble.
Hannibal's needs are particularly illuminated by Livy's account of the forces Philip had available to commit to the war. Although Philip agreed to fight "on land and sea with all his might," the only force of his actually specified is his two hundred ships. Hannibal thus may have felt in special need of naval support--just what Carthage itself should have been most able to provide, but had failed to do so, at least not with any ...