The fantasy way of war?

I was reminded of this problem again while reading Order of the Stick comics looking for the iconic Monster in the Darkness scene, and again by the opening for Valkyria Chronicles, currently on Pete Takeshi's frontpage, although it looks like Valkyria Chronicles had a mild case of it at best. (It also has medevac, Pete Takeshi relates; I may want to look it up.) The problem at hand -- vividly illustrated here, and here, and here -- is that warfare as we know it evolved on account of firepower as we know it. Massed troops were first used on battlefields with no more dangerous ranged weapons than crossbows and catapults. Firearms are predicated on the idea that there are targets on the battlefield that are soft enough that they can damage them (and note that the 16thC musket was a massive, one-caliber weapon firing a two-ounce ball, the only shot heavy enough to punch through plate armor). Heavy fortifications were abandoned after it was no longer conceivable to usefully harden them against artillery and man-portable explosives (and gliders).

Settings that contain massive amounts of firepower without highly advanced technology -- fantasy is of course the primary offender here -- assume that the style of war used in their civilization will be the same as that used in a roughly analogous era on Earth. But medieval castles were constructed on the assumption that no one could easily knock down their walls -- and once that assumption became invalid, castles were completely re-imagined, although only after a rather harrowing hundred years (ca. 1400-1500). So for a fantasy setting to have castles, Lord of the Rings-quality magic is the absolute upper limit, and even then I'm not entirely sure; but magicians who can conjure up earthquakes and supernatural creatures would coexist with massed archer formations for about as long as machine-guns would coexist with armored knights, for exactly the same reason.

So, what should a fantasy setting's style of war look like? ... Well, it would have to involve small numbers of highly-trained elites capable of unleashing massive firepower, who would fight chiefly not by defeating their enemies but by escaping detection by them; fortification would be done carefully and stealthily, and mobility would be a massive part of all military campaigning. In other words: it would look almost exactly like contemporary warfare, as practiced by its best practitioners. In other words, ambushes, patrols, land mines, Ospreys, blooming-lotus assaults, and the siege of Hue City -- massed units of any sort, however fast and powerful, would find themselves harassed, ambushed and bombarded into irrelevance; just ask Saddam Hussein.

Pete Takeshi observed that the fastest way of summarizing this problem -- and the more general issue that fantasy with regularized, powerful magic tends to evolve into much more modern styles of civilization if you think about it long enough -- is to call it the Flintstones Principle.

The definition of the Flintstones Principle is, "If you need a definition for the Flintstones Principle, you shouldn't be writing fantasy."