Sub-Roman Britain (Cavalry etc)

[Conal]

I’m not sure how valid that amount is. No saddle, no trappings, how about fodder and stables etc.? Also, I dare say that you need more than one horse for each cavalryman, plus a herd for breeding. Maybe you’d need 40 cows

That's the point, you can't be sure how valid it is nor can you say, as I have seen often, that a sword would be only applicable to very wealthy when anyone with three cows could apparently get one ... it's open for debate.

These societies were not made up of hunter gatherers but people who had worked the land and raised crops and cattle for centuries, they had enough manpower to refortify hill forts and build massive dykes yet we it appears to be felt that they could not breed enough horses to keep 300 cavalrymen atop a mount.

Societies with much less infrastructure available to them were able to do that .. the Sioux at the Little Big Horn (or Greasy Grass Ridge if you are a Native American) were able to put up 900 -1800 mounted warriors (from a population of just 4,000ish) using quite a large remuda. Admittedly they were a horse led culture but if Sub Roman Britain had a predilection for mounted warfare you would expect a breeding program to cope.

I am of the opinion that it was something other than cost which kept them on foot such as a cultural shift as to who bore arms and who did not. Relying on a professional army for 400 years would not have helped. Where you have a small elite dominating a larger population the tendency is to keep them unarmed and unmartial. Warlords and Tyrants have this habit.

The 1066 Hastings armies were only 7,000 odd, with a few hundred professionals, which is tiny when compared with those of Ceasars time. This illustrates the cultural difference between this new Kingship culture and the Romans and pre-Roman tribal models.

I think you may be along the right lines with internecine strife, together with the new warlord culture, as this is what would take down infrastructure pretty fast.