Great analysis. I agree with you on chariots, as I had the misfortune to try out a unit which promptly lost men, ran amock, and caused more casualties for me than the enemy did...
I've also had some battles in the east with Asabaran-e Madaen (Median Medium Calvary). They are not so great, as among other things, they are in fact a light calvary unit, which I learned much to my surprise during a battle against a far superior force, after having stacked 4 units worth to make up a heavy calvary contingent in an army. They take casualties very easily and have a nasty habit of cutting and running.
Thanvare Parsig (Persian Heavy Archers): Also have the longest range of any of the archer units I've commanded so far, even out-shooting my slingers on many occassions (who usually pack the longest range)
Pantodapoi (Hellenic Native Spearmen): Are very good for garrison duties in non-essential fronts. Cheap and 60 men to a unit!
Shuban-i Fradakshana (Eastern Slingers): Have a better missle attack value than the Hellenic slingers, which means they (should) do more damage.
Usually Theureophoroi (Hellenic Spearmen), Prodromoi (Successor Medium Cavalry) and Sphendonetai (Hellenic Slingers) form the backbone of my early armies (I don't really like phalanxes that much...) until better units come along. These units are amazing and cost-effective for the early game, so I usually fight all of my battles with these and whatever local mercenaries I pick up, while later on I form a seperate stack of Hypaspistai (Hellenic Royal Guard), Pheraspides (Hellenic Royal Guard) and Hetairoi (Companion Cavalry) just for RPing reasons.
Bookmarks