Short addendum: Unmothballing forts does not prevent/cancel movement orders made when the forts were mothballed. It's an uncommon rule, but it could explain some of the weirdness going on with some screenshots people are posting early in wars.
See an example at: http://imgur.com/a/25vmv

In this video I go over fort zone of control mechanics.

Music: Fly away with me
Artist: iamsleepless
   • fly away with me (original song)