Is there a way to force AI's to build corps and armies out of all their individual units when they got the civics for it ? Or to build only corps/armies once they have the civics unlocked ?War wise, AI civs usually don't really get that far against other civs but sometimes do make gains. City states are easily taken, but most AI vs AI wars end up in just a single city, or no cities whatsoever taken. War declarations are mostly appropriate, but they lack the ability to push through the unit walls. In what is kind of counter intuitive, some of the best conquerors I've seen were on lower difficulty levels, with the rare civ (mostly Rome) ends up taking over 1 or 2 other civs completely.
Against humans, they can be a little scary because peace orientated humans tend to have far less troops. But they're still easily outfought using simple tricks that allow you to hold them off long enough to break them. They still are only really properly scary at the very early game, or if you never build any troops. Sometimes a civ with mounted units can still do some harm, as can those that rush down the field cannon line. Their individual unit control is not the worst, but they do really badly at having coordinated goals (missing opportunities to take a city in a turn).
Defensive wise, they're still horrible. The main problem is still that they're unwilling to bring their units towards battle. Often because they're planning to attack some city while being attacked themselves. They build walls way too late because they all avoid masonry now for some reason. At least they sometimes get archers now.
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Or to make them upgrade their units ? (Had England and other blocking tons of sea tiles with 20+ individual archers whilst they got plenty of crossbowman or musketman corps mainland).
The only AI who seemed to make very good use of army civics was China who threw at me at least 15 AT crew armies..but for some reason still had archers and pikemans behind.
I tried upping alot the flavor for "build armies" or something in the files but it didnt seem to change much. If only they would do that, it would cleanup LOTS of space and make for a much easier planning when going to war.