Where did they keep the mules in garrison?

[Paullus Scipio]

Question, is there any consensus about how many animals single legion had?

I have read something about one mule per tent octet and wagon per century. So that is already quite a few hundreds..and obviously artillery etc. would need even more wagons.

...also depends on what period and Legion organisation as well, and no doubt "Table/Establishment" figures had either a shortfall, or were exceeded on any given occasion/campaign, but we can establish rough figures...... a basic figure of one mule per contubernium of 8 men would be right.

For the pre-Flavian Legion of 60 centuries; some 1400 mules ( with a carrying capacity of around 175 metric tonnes)
For the post-Flavian Legion of 59 centuries ( with "double" First cohort); around 1525 Mules ( with a carrying capacity of 190 metric tonnes).
Over these would be the Officer's ( probably down to Centurions) and integral Cavalry (120) horses, say 200 or more horses, allowing a few spares.

These figures include an allowance of 1 mule per centurion, and one for every two cavalrymen (60) plus a proportion of spares. Numbers would change if other animals such as donkeys or camels were used at particular times/places. There is no 'wagon-park' or space for wagons described in pseudo-Hyginus description of the Roman Camp, so wagons were probably not part of the Legion's organic/integral equipment. However supply wagons are shown on both Trajan's and Marcus Aurelius' column, perhaps indicating that these were used by the Supply Train ( the Roman equivalent of the WWII 'Redball Express' ). With regard to the Artillery equipment described by Josephus as being organic to every Legion (Vegetius refers to 55 light 'arrowshooters' - or one per century, implying 59-60 for the earlier organisation; and 10 Heavy 'Stone throwers - one per cohort - for each Legion. These could be carried on light carts ( carroballistae ) with the larger machines broken down for transport. It has been estimated that the Artillery and a modest amount of ammunition would require around a further hundred mule loads, or equivalent in wagons if the Artillery was transported in the Army's Supply Train ( at least the stone-throwers would likely have been)........