| Drimus |
Zombies and most mindless undead usually attack any living creature. Most of the time a necromancer does not need to tell them to attack. They may however need to be told not to attack.
Compelling in this case is being forced to do something they normally will not do. In the game this usually means some form of magical control. While the spell animate dead is magical its duration is instantaneous not permanent. This means one the undead are created they are self-sustaining and no longer dependent on the spell for their existence. You cannot dispel the animate dead to get rid of the undead. The undead created by it are not affected by an anti-magic field. That also means that you can give orders to your zombies in an anti-magic field.
Command undead requires you to expend a channel negative energy. That makes is a super natural ability. This means it does not function in an anti-magic field.
So at the end, what do you think can i order my animated zombies to attack the dread zombies or not?