The opposing army tries to retreat through the same ground occupied by arriving Carthaginian reinforcements. Rome: Total War allows the movement to continue, although the route would fail in reality. Troops filtering back in small groups would meet a fresh force facing the other way and be defeated in detail. Withdrawal routes, reinforcement timing, and control of the enemy's rear matter as much as pressure on the front line.
Notable Point · 3:25:17-3:26:49
Retreat fails when reinforcements block the exit
The game lets an enemy withdraw through arriving Carthaginian troops, although a real force using that route would be destroyed piecemeal.