Thus the foundations of the Mexican empire were hourly loosening, as the great vassals around the capital, on whom it most relied, fell off one after another from their allegiance. The Aztecs, properly so called, formed but a small part of the population of the Valley. This was principally composed of cognate tribes, members of the same great family of the Nahuatlacs who had come upon the plateau at nearly the same time. They were mutual rivals, and were reduced one after another by the more warlike Mexican, who held them in subjection, often by open force, always by fear. Fear was the great principle of cohesion which bound together the discordant members of the monarchy; and this was now fast dissolving before the influence of a power more mighty than that of the Aztec. This, it is true, was not the first time that the conquered races had attempted to recover their independence. But all such attempts had failed for want of concert. It was reserved for the commanding genius of Cortés to extinguish their old hereditary feuds, and, combining their scattered energies, to animate them with a common principle of action.15
Encouraged by this state of things, the Spanish general thought it a favorable moment to press his negotiations