Native Conquest is quite useful for warmongers, as it yields additional Gold sums each time they do what they do best: kill enemies. It will remain useful for the remainder of the game, as long as the condition holds true. Note that the activation of the policy depends on the era the attacking unit belongs to, as compared to the era the defending one belongs to, and not on the era each of their respective civilizations is currently in! So, for example:
- Civ A is in the Modern Era, and Civ B is in the Industrial Era.
- Civ A uses an Infantry to kill a Musketman from Civ B - they will gain Gold (because the Infantry is more advanced than the Musketman).
- Civ A then uses a Knight to kill a Musketman from Civ B - they will not gain Gold, because the Knight is a less advanced unit than the Musketman (even though Civ A is in a more advanced Era than Civ B).
However, for a peaceful civilization, or for one which faces enemies from the same era, this policy is useless.
The first wave of European colonization began in the early 15th Century AD when the Portuguese established trading posts along the coast of Africa on their way to the Far East. But when the Spanish discovered the Americas, soon followed by the Portuguese, English, French, Dutch, Swedes, and anyone else who could sail the oceans, the settlement of “empty” lands took on another tone. For, of course, these lands weren’t empty, but full of natives that had been there for millennia. When the new arrivals clashed with the locals, it turned out poorly for the natives, thanks to Europeans guns, cannons, horses, and diseases.