Project- Influences of Roman military on modern day riot control

[Nathan Ross]

Where should I look for the relevant bits of Polybius and Vegetius?

The Polybius bit has already been quoted a few times already - it's the part where he calls the centurion 'hegemon' - which usually refers to a leader, somebody who goes in front, a front ranker, or a 'head'. It's an inference that this meant he was physically positioned at the front of the century, but quite a good one, I think.

The Vegetius bit has also been quoted, although perhaps not at sufficient length:

II.XIII:...the ensign was inscribed with letters indicating the century’s cohort and ordinal number within it. Seeing and reading this, the soldiers could not stray from their comrades, whatever the confusion of battle. [The ancients] also detailed centurions... wearing transverse crests on their helmets to make it easier for them to be recognised, to command the individual centuries. This was so no deviation should arise, since soldiers in groups of a hundred followed their own ensign and the centurion who had the sign on his helmet.

The last sentence is most important here: centeni milites sequerentur non solum uexillum suum sed etiam centurionem, qui signum habebat in galea

Vegetius is specifically talking about battle, not a march order or anything, and says that the signum and the centurion can be clearly seen by the men of the century (therefore were at the front), and that the troops follow (sequerentur) both of them.

This is, I think, undeniable and explicit evidence for the centurion's position in battle - at the front, with the standard.

If anyone can find evidence for centurions being positioned anywhere else, please do share it!