An hour before the war, the alarm—or more accurately, just hired people yelling—alerted everyone that the war was starting and they ought to get in position.
Some time later, Minko, Sean, and Orz jumped down the wall and ran around the territory, separating directions for maximum efficiency. They maintained their energies, of course, especially since they had no idea where the array was.
They wanted to find the array, hopefully to take down a number before they go and attack the walls. While they couldn't do anything too aggressive, they could cause a lot of trouble and that was enough.
In fact, it wasn't that Fargo and the others didn't think of this loophole. They did, with Belize's guidance.
But they realized a lot of the stronger aborigines they could send to look for the array were all… gone. It was at that moment that they confirmed the Alterrans had been preparing for the war for days.