Quote Originally Posted by paullus
Watchman, the ancients distinguished mercenaries from paid soldiers, even from paid soldiers from allied or subject states. Sometimes the definition got fuzzy, either a) because of the close similarity between paid symmachoi (allies) and actual misthophoroi (mercs), who could easily come from the same city-state, league, tribe, etc, or b) because of the political views of some historian, who preferred to see allies as mercs out of disdain for the hirer.
Seems more like a pragmatic issue of reliability to me, the "paid soldiers" presumably "staying bought" due to (hopefully) having some more motives than the paycheck and the "mercenaries"... well, not necessarily.

At the fundamental level - a man selling his fighting ability and, potentially, life, in return of economic gains - it is difficult to perceive much meaningful division.