From what I've read here on CFC, it would happen occasionally in Vanilla (and PtW), although I don't remember this happening in any of my games. (It's a long time since I played Vanilla, though, and most of those games were at Regent-Monarch, so the AI-Civs generally had fewer units to fight with, promote, and spawn MGLs, than they would have had at e.g. Emperor or Deity). But in nearly 8 years of playing C3C epic-games (mostly at Emperor, occasionally DG), I don't remember ever encountering an AI-Army during any of my wars, neither fighting in the field nor hiding in any town I've captured. This would suggest that no, the C3C-AI tends not to use MGLs to create Armies — or at least, that it doesn't get many opportunities to do so, likely because it doesn't reliably retreat any MGLs that it does manage to win on the battlefield. Probability says that it must (also) occasionally get MGLs during town-defence, but if it doesn't turn those into Armies either, then the only(?) remaining possibilities are that it immediately uses the MGL to rush the town's current project, or that it disbands the MGL. Mods and Scenarios are another matter. When the AI starts the game with an Army (as in the Firaxis Scenario Rise Of Rome), it will usually load at least one unit into them — but it often won't send them out to fight. From what I gether, this is because the AI is programmed to match a potential Army-recruit's M-value with the Army's (current) M-value — but because of the Army-movement bonus (added in Conquests), once the AI puts an M=1 unit into the Army, it is 'forced' to wait until it has an M=2 unit(s) to add to that Army. Or if its first Army-recruit is an M=2 unit, it then 'needs' M=3 unit(s) to fill the Army (i.e. Chinese Riders, or Cavs, in the epic game). So any Armies it does get given for free, tend not to get filled. And because the AI does value its units according to their stats, and is thus unlikely to risk a 400-shield, 4-5HP unit in battlefield combat, when it can send out basic units instead — which have essentially identical A- and D-values, but are vastly cheaper — its Army(s) is usually/ eventually killed 'defending' the city where it started. I do also remember seeing the occasional AI-Army in WorldWide, but again, never in battle, only in a town (and with only 1 unit loaded). And I don't know where those came from (autoproduced, maybe?). ETA: Yes, they were autoproduced. I was reading the WorldWide thread later, and saw mention of at least one Wonder (Terracotta Army, for China) which autoproduces Armies. Putting that together, the best/ only way to allow the Civ3 AI to both acquire and use Armies even close to competently, may be to make Armies autoproduced (e.g. by the epic-game Military Academy — which would itself have to lose the "Requires a victorious Army" flag: maybe require MilTrad plus 10x Barracks built instead?), give the Army-unit a transport-capacity of only 1 but a significant (8–10) HP-bonus as compensation, and (probably) reduce its nominal shield-cost by at least half.