Night battles isolate enemy armies in the campaign

Before attacking, the player checks which enemy formations can join the battle and deliberately chooses a night engagement. In Rome: Total War, that choice isolates the targeted cavalry-heavy army from nearby support. The Carthaginian force can therefore concentrate against one formation without simultaneously fighting the reinforcements on the campaign map. This is a game-rule illustration of defeating separated forces in detail, and it does not imply that darkness automatically prevented historical armies from reinforcing one another.