Defensive lines are NOT intended to STOP the attackers...it is intended to slow down, concentrate and create a PLANNED approach area which is KNOWN and already written down for the artillery and rocket units who are just waiting for the attackers to get to the right place to be RAINED down upon.
The KNOWN AND TRUSTED amount of personell losses while attacking a well planned and executed defensive line is the 3 to 1 loss of personnel to the advantage of the defenders.
The other factors remain open, 3-4 healthy soldiers needed to evacuate a single wounded, loss of leadership creating differing amounts of chaos to lack of knowledge on the actual target, large mined areas creating more losses to the attackers, using extreme amounts of ammo to get little advances, psychological damage to the surviving attackers, loss of support in the civilian population from loss of loved ones, loss of support from outside nations due to lack of advancement toward military goal, needed replacement of lost soldiers by lesser trained and experienced ones, total loss of morale in those who planned the attack when it fails and also the need to clear all obsticles if and when you ever succeed in overtaking the defensive line including not knowing where the mines are and which types can be cleared by magnetic sweepers, non-magnetic sweepers, optical mines, light triggered mines or vibration triggered mines....
