And as far as I understand, each level of wall gets a defense factor, Rams do thier damage (2) * battle modifier * ram weapon/pally if present and if they have enough attack to knock the wall down a level or so it is lowered
(max is the 1420 is the video)
For example:
LVl 16 wall is 579
lvl 15 is 462
117 difference, so it would take 52 rams at 100% battle bonus to reduce the wall from 16 to 15, or 300 for 16 to 0
The catch is like the half way point of wall defense is level 18ish, so it is just as hard to bring a wall from level 20 to level 18 as it is 18 to 0
Sadly, there than added in a hidden multipler that i think deals with how out numbered a side is that heavily affects this system.