If there are, say, 50 of us AFS in that brigade....
And all 50 of us sent 200 def. units...
That's 10,000 defensive units. Maybe it would be wiped out by Zrei, but it would also hurt Zrei's army sufficiently that he may think twice in the future.
If we don't have 200 def. units to spare for reins, we need to get them FAST.