This article serves as an important reminder of the importance of Fear inducing units and is a useful source of tips on how to cope with your Fear !
I have experienced this...
"Until one bad roll causes your best infantry unit to be run down by a slightly larger unit of rag wearing, bone-toting Undead, you don't know Fear." (GW US)
and this...
"All you need to do now is win every round of combat until the Fear-causing unit either runs away (which will never happen in the case of Undead) or is utterly obliterated (if your enemy has Necromancy, again this could be never)." (GW US)
... it's not nice fighting the undead !
Coping with your worst Warhammer nightmare - Fear
It's worth a read.