Where did they keep the mules in garrison?

[Paullus Scipio]

D Campbell wrote:

Paullus Scipio wrote:
The idea that "Many Legions would have absolutely no use for mules, in any case" is about as probable as a modern Western army having absolutely no use for motor vehicles.

Of course, this is a false analogy, as anyone who gives it even a moment's thought can see. A "modern Western army" is paralysed without motor vehicles, which are ubiquitous in society at large. But the mule was not the only beast of burden known to the Romans.

You seem to have missed the point. It is not a false analogy. Mules were ubiquitous in society at large, as motor vehicles are now, and as I tried to demonstrate in my post. Donkeys were perhaps more plentiful, but for general use the mule was the animal of choice, as the words of Varro and Columella demonstrate.
Whether two ox-carts could bring up the Legion's wine ration from the docks of York is immaterial - the Legion could not take the field without it's mules, and that's a fact.