I agree with Al Khalifah

I remember the episode where they were romans and were attacked by Gauls. They decided to place the skirmishes and archers and slingers on hill far ahead of the front line and expect them to be ignored. Of course the Ai just sent a few cavalry units and rode over them like a car goes over a speed bump. They then decided to just hold a small area with their legions. They won because the gaullic charge did not crush them and eventually the gauls ran.
Dunno how they did it.