A readied action, though, is not an interrupt, it's a reaction. If you're using a readied action, you must wait until after the move is completed, then take your action that was readied. This is why you can't interrupt a spellcaster while they are casting a spell -- if you ready an attack for someone to cast a spell against your part, your attack goes off AFTER the spell does.
This is different from the way readied actions worked in 3.5, so it's easy to miss the distinction.
So, in the case of the readied action, the charge would be complete before the readied action could be triggered. Since the charge includes the charge and the attack in a single action, I believe the charging enemy would complete the charge, make the attack, and THEN the fighter with the readied action could do the tide of iron move.
-rg
EDIT:
DOH! I think I'm a huge dumbass!! More being edited soon
New Answer:
Forget everything I just said -- it's been so long since I read through this thread I forgot everything that came before.
You react to each space of movement as a micro-move. So, your opponent moves into range, your readied immediate reaction goes off. You do tide of iron and push the opponent back. That all does work, despite what I said earlier and have struck out to preserve my shame for all eternity.
STILL . . . I would still make the case that unless something has made it impossible for the attacker to complete the charge, and he still has movement, he can continue the charge if he wishes.
Now, an attack that knocks the target prone, immobilizes him, something along those lines -- THAT would work to stop the charge because it would make it impossible to continue. So, if you're really trying to intercept the charge, a grab action might be your best readied action if you have no other options.
It would start to look like a football game, too.
Sorry again for my big mistake. I'm not all that bright . . .
-rg