It would be the "Necessary and Proper Clause" that establishes many implied powers of Congress, since this allows Congress to do whatever is "necessary and proper" to keep the United States functioning.
Hernan cortes was aided by Spain to get gold and silver from the Aztecs or just to explore then he found the Aztec empire. He wasn't aided very well in troops, so sense they carried small pox the Aztecs got infected which killed a big majority of them while the conquistadors also attacked. <span />
