Machiavelli on mercanaries.

[Zimfan]

Just found this digging through the posts here.

https://forums.totalwar.org/vb/showthread.php?t=52733

[naut]

lol

I find that they are useful for adding casualties to a large enemy before my main army strikes the turn after.

[Martok]

They can also be useful for padding out Crusades. Since units in a Crusade army don't cost upkeep, and mercs' hiring cost is only half that of a "national" unit of the same type, you can really fill out a Crusading army's ranks on the cheap.

Of course, I still don't recommend adding a lot of mercenaries to a Crusade since they do generally run like little girls once in combat. The only exception to this rule is artillery--I will hire them in relatively large numbers, particlarly if I can't build that artillery piece myself yet.

[gaijinalways]

I like merc myself. As I posted earlier about my English campaign (on hold as new semester gets ready to start), I use mercs to clean house and conduct my 'dry earth' campaigns. I usually try to bring along some regulars too to get training, with the mercs sometimes selflessly sacrifising themselves for the good of the empire setting up final counter blows by my regulars or just getting mor stars for my generals.

[Mooks]

I like to hire mercs. But only specialty mercs. AKA Extremely powerful archers, pikemen, artillery, heavy horsemen. And so on, basically any unit thats rare and can do some danmage.

[gaijinalways]

Of course, i prefer to hire the speciality units, but sometimes you need units now, and can't wait to train (if possible) or wait to move the units to where you need them.

[Deus ret.]

In concordance with Martok's statement I rely on mercenaries almost exclusively as artillery supply. The reasons are simple:
1. with those units, morale practically doesn't matter at all and
2. it takes up quite some time and effort to build them myself, thereby preventing provinces from churning out more useful troops. This is especially valid for small factions, and in MedMod, the siege engineer is a unique building, making it even more attractive / compelling to scoop from the mercenary pool.

The remaining mercenary types are only relied upon in emergency situations. More than once I witnessed proud kwarazmian cav rout shortly after slamming into the exposed flank of some FMAA so even if I recruit them, it is mostly to quickly beef up my forces in order to avoid a difficult offensive battle through sheer numbers.