Does anyone else find the mercenary industry a strange thing in war? Business dealings made under the assumptions of the status quo, between entities who are able to entirely change what the status quo is in an instant
Get paid in gold or diamonds. Also you can take a bet that property given to you in occupied territory will remain in your possession after hostilities. This is what Hitler did in ww2 to retain his generals' loyalty.
Many have mentioned Machiavelli on the untrustworthiness of mercenaries, but looking at it from their point of view (eg. Xenophon's 10'000) I'd guess most mercenaries are well aware that with little loyalty going the other direction, they're the most likely to get tossed under the proverbial bus/off the proverbial troika.