If a unit attacked another, so it is protruding! And subsequently decides to withdraw, does it fall back into its original square or the one behind?
This can be important if the original square is a echelons as it can't withdraw off table?
Im not sure what you mean about withdrawing in the same move as it attacks, unless you mean post melee. The defender has the option to withdraw risking casualties prior to the fight.
If you mean post the fight which is lost by the attacker, They simply fall back into the original square from which they attacked from. Not sure about the echelon reference?
The situation was, an unit attacked, in round one had the same hits so static melee. With no dead!
In the next round in the opponents turn it rolled badly and got mauled.
It then wanted to cut its losses and withdraw as it was now outnumbered,
So does it withdraw to its start square or the one behind the start square? As it's still protruding!
The problem is caused by using hits rather than casualties, a unit can "win" the melee and loose lots of men,
In other periods the loser would fall back bouncing back if the losing attacker, but these rules don't have that mechanism. The makers continue until withdraw or rout?
What was annoying was the attacker was the Saxon all armoured unit, which took 3 hits and rolled three ones, lost leader and 2 armoured in the front rank, and was now a general and 2 armoured warriors were left!
I can see how that could be annoying with your best unit! Again without the rules to hand, I'd suggest that they fall back to the square they came from as they are currently occupying the opponents square in a continuing fight.
Afaics, 'protrusion' is just to indicate who started the fight. The attacking unit does not actually enter the defender's square (p.86). So the withdrawal move would be taken from its (i.e. the attacker's) square, not the defender's.