Naval battles cannot be fought directly, which makes them a tactical abstraction. Campaign movement still depends on ships: an army needs transport to cross the water and land. A port is left unblocked until a strong enough fleet can be built, and the planned expedition to Carthage cannot sail without enough vessels. The campaign map therefore gives maritime strength real control over movement and pressure even though the player never commands a naval battle.
Notable Point · 47:48-52:17
Fleet strength still governs amphibious access
Rome: Total War resolves naval fighting outside the tactical battle screen, yet fleets still determine whether an army can cross by sea and whether a port can be blockaded.