The White Conquerors

The Aztecs were a mighty civilization, conquering and enslaving other Mesoamerican civilizations, ruling with terror and might, and at the peak of its power under the Emperor Montezuma II. Their hand of power stretched over Mesoamerica, even over the Mayans, but newcomers threaten their land, their stability, their rule, white men who came on ships, and on animals never before seen in the land, horses. What match would these Aztec conquerors be for the freshly arrived white conquerors?