The tribunes having thus organized the troops and ordered them to arm themselves in this manner, dismiss them to their homes.
When the day comes on which they have all sworn to attend at the place appointed by the consuls —
each consul as a rule appointing a separate rendezvous for his own troops, since each has received his share of the allies and two Roman legions —
none of those on the roll ever fail to appear, no excuse at all being admitted except adverse omens or absolute impossibility.
The allies having now assembled also at the same places as the Romans, their organization and command are undertaken by the officers appointed by the consuls known as praefecti sociorum and twelve in number.
They first of all select for the consuls for the whole force of allies assembled the horsemen and footmen most fitted for actual service, these being known as extraordinarii, that is "select."
The total number of allied infantry is usually equal to that of the Romans, while the cavalry are three times as many.
Of these they assign about a third of the cavalry and a fifth of the infantry to the picked corps; the rest they divide into two bodies, one known as the right wing and the other as the left.
When these arrangements have been made, the tribunes take both the Romans and allies and pitch their camp, one simple plan of camp being adopted at all times and in all pieces.
I think, therefore, it will be in place here to attempt, as far as words can do so, to convey to my readers a notion of the disposition of the forces when on the march, when encamped, and when in action.
For who is so averse to all noble and excellent performance as not to be inclined to take a little extra trouble to understand matters like this, of which when he has once read he will be well informed about one of those things really worth studying and worth knowing?
Walbank Commentary