The AI for Field of Glory II has been developed by building on the knowledge gained from developing the generally praised AI for Pike and Shot and Sengoku Jidai.
For non-preset scenarios, it is important that the AI can deploy its army in a sensible formation, taking account of the prevailing terrain. Generally speaking, most ancient armies would deploy with an infantry centre in one or more lines. (Usually three for Romans, usually only one for Hellenistic armies). They would then have cavalry on both wings and perhaps in reserve, plus light troops both in the centre and on the wings. Except for cavalry armies, the “autodeploy” routine therefore starts with the infantry centre, in one or more solid lines. If the army has a mixture of heavy and medium foot, it will deploy the heavy foot where the terrain is most open, and the medium foot where it is most uneven. This takes into account not just the deployment line but also the map in front of where the line will advance.
If it is possible to rest one flank of the infantry on a river or a coastline, it will do so.
Cavalry are then assigned to each wing depending on the amount of adverse terrain on each wing. More cavalry will be deployed on an open wing than on one with lots of rough or difficult terrain or a river. Some cavalry may be assigned to a reserve behind the infantry.
Light troops are then assigned in a similar way to the cavalry, but more light foot will be deployed on the wing with more terrain, and more light horse on the more open wing.
For cavalry armies, the cavalry is divided into centre and two wings, and the usually weak infantry deployed at the back in reserve.
Read the full A.I. Developers Diary HERE.