Vexillation deployment question

[dadlamassu]

Vexillationes were of differing sizes, and men of differing rank were appointed to lead them. During the 1st century, it seems to have been most common for one of the legion tribunes - or even an equestrian officer from another unit - or perhaps the primus pilus of one of the legions involved to be appointed as commander of a larger detachment (vexillations for some reason seem often to have been composed of men drawn from several different legions rather than just one).

In the case of smaller detachments, a centurion may have been appointed as praepositus vexillationis.

This 2004 paper by Geoffrey Tully covers the topic of vexillation command quite well: Did Centurions lead Detachments of their Legions in Wartime?

Thank you very much for the answer and the link to the paper.  A very interesting and useful read.