Actually something along the lines of this would happen:
Town A and B trade often.
Town C comes in and destroys town A. Town C has a raiding party of 10 or more.
Town B realises town A has been destroyed, and set up a 3 or 4 man hunting party to find the criminals.
While they're gone, Town C stumbles upon town B and plunders it too, leaving the group stunned when they return.
Town D gets word that two nearby towns have been raided, and attempt to bolster their defenses. Town B joins them.
Too late - Town C discovers town D along with town B's men and lays waste to everything and everyone there too.
Town E is scared shitless and submits to town C's will. They get ransacked anyway, because town C loves to grief.
In the end:
Town C's town is untouched, because the other towns haven't had a chance to respond before dying, let alone kill the swarm party or track them back to their town.
Town A, B, C and D are destroyed with 15 or so dead.
Town C proceeds to circle jerk over their griefing spree, building swastikas and the like.
You probably know who I'm referring to by now.