And if they get eliminated, the next in line steps up to the plate, and so on. I'm on the slightly-doubting side myself, but it does have the nice side effect of limiting the amount of time that you spend with the die. The sole effects of broken bands are to count towards the rout of the parent unit, and have much reduced melee strength. Strangely, missile fire is a casualties-only affair. No morale checks, ever, even if you score multiple casualties.
Movement is regulated by a written orders system.
There are explicit rules for playing without it, but the rules make it clear that you're a wimp if you do so. Pivoting requires a dieroll vs a leader-dependent range, so movement in any direction other than straight ahead is difficult. The Scots are irritatingly prone to follow their own muse, making any sort of grand tactics hard to implement. So they can sometimes instantly react to events on the field. I managed to play through a solo game in a few hours.