I just thought about naval warfare in the late industrial/modern era and came up with a few ideas. - Aircraft carriers come with carrier air groups automatically upon construction, and end the use of aircraft carriers for airbases by land-based air groups. - With the new CAG design on the carriers, add an order for air strike on the list of buttons among the movement and fortify buttons. - You should be able to specialize ships for specific purposes, such as adding cruise missile capabilities to destroyers to make guided missile destroyers or the anti-air AEGIS system to a light cruiser (thus creating an AEGIS cruiser). - Allow construction of lighter and less expensive capital ships such as heavy cruisers and battlecruisers as well as fleet support units like light cruisers and destroyers. - Upgrade capital ship units (battleships, carriers, battlecruisers, and heavy cruisers) to be powered by nuclear reactors after discovering nuclear power, being parallel to the advent of nuclear submarines, but make it expensive to simulate retrofitting an older vessel to modern capabilities. - In the modern era, make carriers the all-powerful capital ship with aircraft bombardment (vice usage of the big guns) superior in every way to the firepower of the battleships, battlecruisers, and heavy cruisers, but allow the other capital ships to be refitted with guided missile systems to compensate for the inferior firepower. But the refitting will cost a bit and it would be more practical to get the firepower stock on a carrier than refitting another type of capital ship after building it, so this would cause a fall out in the number of non-carrier capital ships seen in the navies of the world. - Have submarines upgrade to attack submarines, and make SSBNs a separate class of warship. - Have the ability to organize ships into fleets that can operate in a certain radius of squares, yet can only go so far from a friendly port. This seems to be a lot of micromanagement, but I think that it could be implemented well to more accurately modern naval warfare than in Civ3.