the rules say no premade defence but as soon as you start playing u can but your guns were ever you want, i was meaning that in some maps there are neautral bunkers that is like regular houses evry one can enter and there are trenches that look cool but realy are wide holes with heavy cover as seen on the first american campaing. and i realy didnt think about the mortar... i get your point evry one you use that, thats cinda sad cuse it would porobably destroy the dead stall but i gues you will have to ceep a backup force to fill up teh trenches with after each barage.