Dunno. Is it a breakthrough (for the AI as of the latest patch) or a glitch. I was facing [attacking] 3 militia units of AI (in a campaign) with a fully army of spear levy and 2 parrot guns. I had to WORK my ass off maneuvering to get to the militia [who were taking proper cover on a wooded hill]... whereas previously the AI would just charge my line if faced with artillery. If this is consistent: great work CA!