On the chapter regarding Columbus:
A third important development was ideological or even theological: amassing wealth and dominating other people came to be positively valued as the key means of winning esteem on earth and salvation in the hereafter. As Columbus put it, “Gold is most excellent; gold constitutes treasure; and he who has it does all he wants in the world, and can even lift souls up to Paradise.” In 1005 the Vikings intended only to settle Vineland, their name for New England and the maritime provinces of Canada. By 1493 Columbus planned to plunder Haiti. [...]
High school students don’t usually think about the rise of Europe to world domination. It is rarely presented as a question. It seems natural, a given, not something that needs to be explained. Deep down, our culture encourages us to imagine that we are richer and more powerful because we’re smarter. [...]
Also left festering is the notion that “it’s natural” for one group to dominate another. While history brims with examples of national domination, it also is full of counterexamples. The way American history textbooks treat Columbus reinforces the tendency not to think about the process of domination. The traditional picture of Columbus landing on the American shore shows him dominating immediately, and this is based on fact: Columbus claimed everything he saw right off the boat. When textbooks celebrate this process, they imply that taking the land and dominating the natives were inevitable, if not natural.
Most important, his purpose from the beginning was not mere exploration or even trade, but conquest and exploitation, for which he used religion as a rationale. If textbooks included these facts, they might induce students to think intelligently about why the West dominates the world today. [emphasis mine]
One of the many, many issues I have with King Caspian's actions in the last Narnia post, as well as the way in which his actions are described in the text, is that claiming dominion over a land (and any native population therein, since no exhaustive search is made on any of the "uninhabited" islands to make sure that none of the inhabiting plants, trees, animals, etc. are sentient, nor would such a search be feasible since the humans on the Dawn Treader cannot travel to and/or survive in every environment in which a sentient plant or animal could thrive) is treated as a perfectly natural thing to do. No other possible alternative action is even hinted at, let alone made out to be potentially more desirable and/or more moral than absolute and eternal dominion of the lands and people therein.
This isn't academic, nor was C.S. Lewis unaware of the problems with colonialism, yet it's what we're given in Narnia: unabashed cultural domination without a hint that there might be other, better ways to interact with different places and people.