 Lucius Marcius noticed that the Carthaginians were careless in guarding their camps and devised a plan.He considered that it was easier to attack Hasdrubal's camp while he was alone, before the three Carthaginian commanders might unite - the other Carthaginian camps were six miles beyond Hasdrubal's.A Roman contingent with some cavalry hid in a thickly wooded valley between the enemy camps, which cut off the road.