I finished reading Ghosts of Cannae. Very readable and enjoyable military history of the Second Punic War. Hannibal invaded Italy with enormous success, winning devastating tactical victories at Trasimene and Cannae. But he never translated those victories into strategic success, Rome stood undeterred. In a sense Hannibal was outclassed. Rome was not ruled by any warlord or Greek despot willing to make peace based on a rational calculation of interest. Instead it was already an empire with unmatched manpower and a Senate determined to win at all costs. If that meant sacking their own major cities like Capua then so be it.
Capua is instructive. They accepted Hannibal's offer to break off from Rome on the condition that they didn't need to contribute soldiers. That left Hannibal with the liability of protecting the city but no additional assets to do the job. An impossible situation, one quickly exploited by Rome. Hannibal couldn't win by being a mere warlord, he needed to make the conflict with Rome into a civil war instead of just a foreign invasion. That meant giving dissident latins something to fight for, they needed an ideology or an idea that was worth dying for. Hannibal couldn't just break up Rome, he needed to create an alternative. Instead, Rome created a new Hannibal in the form of Scipio Africanus and the rest is history.
The book references a provocative thesis I hadn't seen before: That the Republic fell because Rome couldn't meet its military challenges without powerful and charismatic generals, and that this was Hannibal's ultimate legacy. This seems a bit off- Rome did quite well isolating and marginalizing Hannibal without a superstar. The only way Scipio is necessary is if you think Rome would have run out of willing soldiers, and there's nothing to support that. How different would things be if Publius Scipio died at Cannae!