Is there a 'realistic' use for mercenaries?

[O'ETAIPOS]

For hellenistic armies mercenaries were a way to have profesional corps of men able to stay in service all year round. As such the most common use was to garnison rebel prone lands and border fortreses. Majority of merc were never used in "Great" battles, as during main campain somebody have to guard your back especially as your levy is away.

That said it was quite common to recruit as merc people from rebel prone areas as a way to drain those places from most aggresive and warlike elements. And then send them to some difficult post or into heavy fighting.

[TWFanatic]

I don't see why you would wish to waist mercenaries, incredibley expensive as they are. I always use crappy levy troops for the deadliest jobs, such as storming walls. They're cheap!

[palmtree]

Indeed. No sense throwing Mercenaries away. They're harder to replace than regular troops and twice as expensive, but don't cost any more in upkeep I've found.

[Starforge]

I prefer my native troops - even the poorer ones - to learn from experience. Using the Mercs in the manner you described might save me some troops but certainly cost me a chevron or 3. Even those cheap native levy troops start to become pretty effective once they've gotten into the silver chevrons.

I rarely hire Mercs unless I expect an immenent attack and don't have enough native troops nearby OR if I overextend myself a bit and need some extra troops for garrison duty.

[Danest]

I use my mercenaries and reserves, missile, and flanking troops, due to the fact that they can't be retrained, and so any experience they earn will be useless if they are sufficiently depleted.

[LorDBulA]

If I have a choice I dont use mercenaries for suicidal missions.
They are very expensive to replace but are not expensive to upkeep.
From financial point of view it doesnt make sense to hire mercenaries and annihilate them in first battle.
That said it had happened few times. But I just didnt have a choice.
You just cant assault city with hors army.

[Sarkiss]

If I have a choice I dont use mercenaries for suicidal missions.
They are very expensive to replace but are not expensive to upkeep.
From financial point of view it doesnt make sense to hire mercenaries and annihilate them in first battle.
That said it had happened few times. But I just didnt have a choice.
You just cant assault city with horse army.

agreed.
in any battle i fight i throw them in only if absolutely nessecary, otherwise they are kept as reserves (in most cases).
main reasons they are so valuble to me -
1. they are very expensive to hire anew.
2. you cant retrain them in most cases.
3. like said above, they can fill the gap in what otherwise just isnt your faction's strong point.