When Cortes landed on the coast of Mexico, he was emboldened by the Bulls of Donation. These were edicts from the Catholic Pope that essentially “gave” Mexico and Central America to the kingdoms of Castile and León--that is, Spain.
Spain followed up the papal edict with the Requerimiento, a document written by the Council of Castile that declared their divinely ordained right to take possession of the territories of the New World and to subjugate, exploit, and kill the native inhabitants.
During Spain’s wars against the Moors in the 15th century, Spanish religious leaders asserted that because Muslims had knowledge of Christ yet rejected him, waging a holy crusade against them was legitimate. However, this theory did nothing to legitimize Spain’s wars against native peoples in the Americas, who had no knowledge of Christ. The Requerimiento provided not just the legal, but also the religious justification for conquest of the Americas.
Before Spanish forces forcibly entered a populated area, the Requerimiento was supposed to be read aloud to Native Americans to inform them of Spain's rights to conquest. It didn’t matter if the locals didn’t understand Spanish. The Spaniards had given themselves legal grounds to consider anyone who resisted as defying the will of God.
In the first episode of Aztec Empire, I wrote a scene in which the Spanish conquistadors formally read the Requerimiento aloud to a group of perplexed and angry Maya before invading their land. In this case a translator (Aguilar) was present, but that was extreemly rare. As far as the conquistadors were concerned, this document authorized them to do pretty much whatever they wanted.
The first few paragraphs of the Requerimiento attempt to explain the origins of the Papacy to the natives. Additional paragraphs then explain the “donation” of the Americas to Spain by the Pope. The document ends with a chilling threat to the wives and children of the natives if they don’t comply:
“I certify to you that, with the help of God, we shall powerfully enter into your country, and shall make war against you in all ways and manners that we can, and shall subject you to the yoke and obedience of the Church and of their Highnesses; we shall take you and your wives and your children, and shall make slaves of them, and as such shall sell and dispose of them as their Highnesses may command; and we shall take away your goods, and shall do you all the mischief and damage that we can, as to vassals who do not obey, and refuse to receive their lord, and resist and contradict him; and we protest that the deaths and losses which shall accrue from this are your fault, and not that of their Highnesses, or ours, nor of these cavaliers who come with us.”
The final line about deaths and losses being their fault is classic "blame the victim." Such attitudes have been prevalent throughout history. A current example would be: the unarmed person committing a misdemeanor wouldn't have been killed if they had followed orders.
Just because something is legal, or even excusable, that doesn't make it moral.