I had this weird situation the other day. I invade a province that had just a few peasants in in with 400 of my men and pressed 'End of Turn'. During the opponents phase the enemy moved 600 units in to defend. I though ok, and reloaded.

This time I moved in 700 of my men and upon pressing End of Turn the enemy now moved in like 950 or so.

I always thought all the turns were taken 'simultaneously' but this clearly proves otherwise.