Spanish conquistador Cortez gathered Aztec enemies to help in his initial assaults on Moctezuma's forces. Once captured, the Aztec ruler was forced to rule on Spain's behalf; meanwhile Spaniards insinuated themselves throughout the  empire, at which point, Moctezuma could be killed. Divide and conquer was a strategy that served Europeans well in their conflicts with Natives well into the 19th century. (Do you think that the prince's "spear" in the absurd clip from the Italian film Hercules Against the Sons of the Sun is a euphemism?!)

Sources: Captain from Castille (1947); The History Channel: “History for Kids”; Hercules against the Sons of the Sun (1965);