Well I burnt the midnight oil and have now managed to build two historical battles from scratch. I kept a note of what files did what and wrote this up into a guide which I have posted in the MTW forum. I managed to change the factions for both MTW and Viking TW, faction affliation, allies, text files, position on the map. I am now experimenting on getting the ai to behave differently - first try, an ambush situation in a mountain pass. I want the ambush unit to wait until the decoy unit is attacked. I will let you know how I get on.