I always laugh then the AI builds stupid citty raider catapults. I'll constantly see the AI move a stack next to my well defended city, then attack with those stupid upgraded cats. Umm, what is the point? So what if you can do MORE damage to my #1 defending unit in the city. The big point is... When the other units attack, my units will autorotate so the next strongest unit will defend, and so on. Thus, by not using barrage, the AI screws itself by having to attack stronger units than it should on the mop-up attack. But always, if Firaxis fixed this, our games would be a little harder to win.