[split] Phalanx warfare: use of the spear

[Paul Bardunias]

and how would they know they are not winning? by them being pushed back? that would just make them pushing harder...for the worst for the guys in the front row.. Until these guys are somehow physically threatened, they would not rout..  so you would have to flank them or something... but i dont see how would they start panic sooner than those in front rank

It is a maxim of combat formations that all routs start from the rear.  You can panic all you want in the front rank, but you have no way of escaping, so you either keep fighting or fall down.  This effect, the morale bonus of men behind you that make it impossible to retreat is one of the main reasons given for deep ranks by those who doubt othismos, Like Goldsworthy.  I think it is surely at play, but only part of the answer.