 Just as in the case of the regimental colors or flags of early modern Western regiments, the "vexillum" was a treasured symbol of the military unit that it represented and it was closely defended in combat.It was the main standard of some types of units, especially cavalry; however, it was regarded as less important than a legion's "aquila", or eagle, and may have represented a subdivision of a legion.However, that is not entirely clear from surviving sources (see "vexillatio").