This little diagram shows the zombie conga in action - use the buttons to make the units move.
The enemy has a unit that the Vampire Count player does not want to have charging his unit.
Therefore he conjures up a unit of zombies, in a long line, forcing the enemy to charge them if he wants to get into combat.
This is advantageous because the enemy will not kill more than 1 or 2 zombies, and Ranks, banner and outnumber will mean that some zombies are left.
In the next vampire turn, the vampire unit counter-charges!