How do the reconquista and spanish conquests in central and south america reflect the crusading ethos of the late middle ages? how was the conquest of the aztec empire achieved?

Regarding the first question, let´s say that the strongest motivation of the Spanish conquerors was a search for personal wealth, titles and social recognition, advantages that were only reserved to noble men in Spain. In the New World, they could become masters, encomenderos, big landowners and possess large numbers of Indians as forced labor. After arriving , they got in contact with large non-Christian populations. So, the conquering impetus inherited from the Reconquista and a zeal to spread the Christian faith in the new lands (somewhat related  with the fight against the Moors) combine in the conquest of Central and South America.

The Spanish conquest of the Aztec empire was a combination of smart military alliances with peoples subjugated by the Aztecs and who hated them, shrewdness, treachery and betrayal on the side of the Spanish troops and their leader Hernán Cortés.

Explanation:

the american civil war was not caused   by slavery but by economic factors.