The leader of the Aztecs at the time of their defeat in 1519 was _____ AP American History The leader of the Aztecs at the time of their defeat in 1519 was _____ A. Atahualpa B. Moctezuma C. Tenochtitlan D. Texcoco E. Geronimo Answer: B Share this Share on FacebookTweet on TwitterPlus on Google+