Not sure if we should've done that though... If we're in the region he can use his magic on us!
But yeah... it should've been properly announced at least a day ahead. And it should've been decided by all the generals to attack. I mean, Thal still has 5K more to throw at him... They're just not in position yet. And I'm sure OG could've conjured up some more too. Oh well, 2nd round reinforcements I guess.
I was seriously considering looting the region to damage the roads, to delay travel, so you arrive piecemeal... that would've been evil, and very effective.
But, unfortunately, for this battle Overlord has pretty much decided to use nothing but brute force, because he wants to show humans how weak they are, and leave them no excuses. Using magic or delays or any other trickery would've given them an excuse. So sad. :-(