You will be able to do this better in the coming months with your own units. right now having units on the walls looks pretty silly i know, later on they will align to the walls in proper orientation and possibly give every battalion a new submenu of buttons for multiple commands such as patrol the walls and other interesting features to make a battalion disband formation to man the walls and spread out over them.
We actually have a prototype testmap where you press a button and it tasks all your units to evenly align in a line along your walls, all around the layer of walls, but it needs work to properly work in a real game.
Joseph B. Visscher - JBV3737
Bugs aren't the problem, figuring out how to fix them is.