Quote Originally Posted by econ21
4 stacks simultaneously? I could not do that. I'd be struggling to beat 2. I tend to use fairly conventional tactics (line em up, go for good match ups, try to flank). Sheer weight of numbers will overwhelm a conventional battle line.
You can do that fairly easily if your general has 8 or more stars and you only face captains. Then you need Heavy Cavalry and Infantry. Surround the individual stacks and they rout easily. When routing you mow them down without taking any losses. You have to play that very offensively.

The campaign AI could do better. It should know exactly what to build and where to build. It should be able to plan further in advance than humans can. It should be better at calculating upkeep costs. It should frustrate the hell out of you in a good way because it's always better off than you and it has the better troops.
The battle AI should know exactly in which microsecond it needs to issue the retreat order for skirmish units. It should be impossible to catch an archer unit before it retreats behind a spear line. It should constantly adapt to your manouvering and outmanouver you. It should be able to read the battlefield better than humans because it knows its height and terrain values in exact numbers that translate in increase of kill rates for archers. It should be able to time the charge of the infantry line with the flanking cavalry exactly down to the millisecond. And so on, you get the picture.