Okay, this is my hypothesis:

I have 25 Skeleton Archers, and I spray arrows all around me, happy and content. This unit is formed in a straight line, and together with another one like it covers most of the table's width. Behind this unit (by its right edge) I have, say, a unit of Ushabti. The enemy crashes into my archer unit, rips the skeletons apart (as usual). Now, as he kills models, I remove the skeletons that are right in front of the enemy unit, probably halving it or something. Anyway, I remove a bunch of skeletons, so many that the enemy unit is no longer in contact with my own.

Now, in the Big Red Book it says (page 46) that units who are no longer in contact with the enemy must be moved along so that they remain in contact. It does also say, though, that this only occurs when units charge others in the rear or charge single-rank units in the flank - did I miss some rule that says I can't remove these models?

Assuming I didn't, then I should by selecting models from each end of the unit, be able to control exactly how far to the side the enemy unit moves, thus setting it up for a flank charge by the Ushabti. In addition, though this is only barely related, I can heal up the skeleton unit when the next turn rolls around, adding models to the rear rank and giving myself a rank bonus to add to the coming smackdown. Unless I've missed something, this (admittedly very cheap) tactic could potentially let one do a lot of damage and lessen the need for reforms in order to take charges. If you can't keep the enemy from charging your single skeleton unit with every one of his own and grinding them to bonemeal, this one is pretty doomed one your opponent has seen it.

But here's the question, since I'm sure a lot of you are already laughing: what did I miss, that makes this impossible?

You can't remove the models in contact, you have to start with those not incontact.

Dreadful, but I figured it was something like that.

Edit: Wait a stinkin' minute here. I can't see this anywhere in the book.

u can see it like that: when 1 model die another 1 take his place:D