The Wealth of Nations by Part 3 Chapter 3 Page 12

and the king to support them against the lords. They were the enemies of his enemies, and it was his interest to render them as secure and independent of those enemies as he could. By granting them magistrates of their own, the privilege of making bye-laws for their own government, that of building walls for their own defence, and that of reducing all their inhabitants under a sort of military discipline, he gave them all the means of security and independency of the barons which it was in his power to bestow.

Without the establishment of some regular government of this kind, without some authority to compel their inhabitants to act according to some certain plan or system, no voluntary league of mutual defence could either have afforded them any permanent security, or have enabled them to give the king any considerable