The point about Hannibal is that the Romans [of that period] didn’t surrender. The Senate refused to ransom captives from Cannae. Survivors were banished to Sicily [despite Rome’s need for trained manpower. The Senate would not allow captives’ families to ransom them. The romans refused to receive Hannibals peace emissary after the battle of Cannae. They never listened to his peace terms. When Hannibal finally got to Rome, the Senate sold the land he was camped on at full market price. Romans didn’t surrender. they just doubled down.
The Rome of Augustus was most definitely not the Rome of Scipio or Fabius.
The Roman Republic had been demoralized and destroyed by a century of horrific civil war and recurrent “legal” massacres by proscription. Or Augustus would never have been able to acquire and keep absolute power.
Speaking of Fabius, his tactics would make all the Marine advantages pretty useless.