Jack did not mind the guy's insensitive comment, he was just glad that this would be over soon.
He heard some drumming sound in the distance. The orcs started to move away after this drum sound was heard. He assumed the sound contained some messages that only the orc understood. This must be how they communicated in the field, since they didn't have instant communication system like the players. That sound just now must have called for them to regroup with the main army.
As the orcs left, they also headed in the same direction, making sure not to get too close with the marching orcs.
