When the site for the camp has been chosen, the position in it giving the best general view and most suitable for issuing orders is assigned to the general's tent (praetorium).
Fixing an ensign on the spot where they are about to pitch it, they measure off round this ensign a square plot of ground each side of which is one hundred feet distant, so that the total area measure four plethra.
Along one side of this square in the direction which seems to give the greatest facilities for watering and foraging, the Roman legions are disposed as follows.
As I have said, there are six tribunes in each legion; and since each consul has always two Roman legions with him, it is evident that there are twelve tribunes in the army of each.
They place then the tents of these all in one line parallel to the side of the square selected and fifty feet distant from it, to give room for the horses, mules, and baggage of the tribunes.
These tents are pitched with their backs turned to the praetorium and facing the outer side of the camp, a direction of which I will always speak as "the front."
The tents of the tribunes are at an equal distance from each other, and at such a distance that they extend along the whole breadth of the space occupied by the legions.
Walbank Commentary