He burned the boats and decided to conquer the Aztecs against orders after witnessing their ritual child sacrifice. The popular history regarding Cortes and the Spanish is largely a result of hyperbolic propaganda during the time period against Catholic interest by protestant interests, mainly Elizabethan England. https://www.npr.org/sections/thetwo-way/2017/07/05/535613480/aztec-tower-of-skulls-reveals-women-children-were-sacrificed