In both the case of Spanish forces under Cortés and Spanish forces under Pizarro, what elements led to Spanish victories and territory control?

There are many factors that gave the Spaniards the upper hand in con-questing the American Civilization. The Spaniards have superior weapons and even their less sophisticated weapons like crossbow and steel spar heads were superior to the native American civilization. Secondly, the use of gun powder by the Spaniards shocked the indigenous tribes, which have no answer to them. The horses provide greater mobility to the conquers while natives use IIama which is less suitable for horses. And last but not the least is the diseases Spaniards carried with them, which eliminated a large native population.