cthia wrote:US carriers are not forts. They are the legions of firepower you can send out without worry because your home position takes care of itself. It is naturally fortified by location. Carriers are projected hulls of force. And, do recall, they did sit at home once upon a time before the Japanese showed them the error in that. However, there are many forts, bases, littered along the landscape minding the store. They are not surrounding Wash. D.C.
I'd agree that carrier's aren't forts. To the extent the US has a significant homeland defense it's the various DoD fighters and bombers at various Air Force bases and Naval air stations. So sometimes the same kinds of planes a weapons a carrier but at a much cheaper fixed airbase.
Though roll back in time about 50 years and DC and plenty of other major US cities were ringed with batteries of conventional and nuclear armed Nike missiles - primarily designed for surface to air against Soviet bomber formations but capable of a secondary role as a surface to surface missile against naval threats. But then the threat switched from bombers - which you could to an extent still fortify against - to ICBMs which you practically couldn't. And then defense switched from fortification to treaties and mutually assured destruction, with focus on 2nd strike capabilities.
Now Nike batteries aren't exactly forts - it wasn't possible to armor the missile launchers and their radars against nuclear bombs. But they were heavy defenses set up to protect cities and the people and industry within them.
But even up into WWII there were more classic gun fortifications protecting major coastal cities (I've hiked up to the 16" batteries on the Marin Headlands that were installed in the 30s to beef up the defenses around the entrance of San Francisco bay. And of course the Hawaiian islands had a fair amount of light, medium, and heavy coast defense artillery
(which somehow never gets mentioned in various alternate history stories about Japan following up the attack with an invasion). And then the "concrete battleship" of Fort Drum in the Philippians was a tough nut for Japan to crack (unfortunately successes elsewhere meant they were able to take Manila without having to destroy or get past that particular fortification)
So when the threat to cities and naval bases was primarily from other navies lots of money was spend building fortifications to defend them. (Admittedly the major coastal cities tended to be where the naval shipyards were - so defending them preserved both the economic power of the nation and it's shipbuilding capability. Both as important, long term, as its current fleet.
Now the threat, most places, is from air attack. So the defenses focus on airfields for your fighters and surface to air missile networks - not massive gun armed concrete forts. Also we seem to have reached an oscillation in the tug of war between armor and weapons where it's not possible to armor the critical bits against the precision weapons coming after them. So suitability of defenses it based far more on redundancy, misdirection, and mobility -- avoiding getting hit, or having additional radars and missiles that can come online if as others are lost.
But defenses in the Honorverse are fairly survivable against the best weapons available - so it makes sense again to build fortifications (though in some ways they are conceptually closer to a Crimean war floating ironclad gun battery than a classic coastal defense fort - since they are in many way a very heavily defended, very slow, ship with heavy firepower.