Quote Originally Posted by The_Mark
I am

Keep in mind, though, that the AI might (read: will) have some (read: lot) strange quirks sometimes (read: always). Anyway, that's the case in 1.2, I'm not that sure about 1.3/BI, as I haven't modded it. E.g. at least in 1.2 the AI could use the troops as skirmishers, advancing them to the front to pepper the enemy (and taking immense casualties from unfriendly javelins while doing so).
Arg, this seems to be the case. If you remove the prec ability from all pilum units, then change them from heavy_pilum_infantry (or light) to just heavy infantry and put in the default melee state defend, engage_at_will, fire_at_will, sometimes the AI units will fight just like I want them to, other times they will run around like they have hot potatoes in their pants...

I don't know why they choose to skirimish. I am having a problem though, the Roman troops won't form their normal 3 lines, so I am hoping someone with more experience with formations can try this out by modifying the formations text and removing the prec ability from troops so pilum troops throw both pilums and don't necessarily charge before going into combat.