All that is required for evil to succeed, is that good men do nothing. The major force in world history is sheer dumbness. The peasants always get screwed. What makes you strong can kill you in the end. People are consistently supid throughout history.
Superior firepower is important.
To understand people look at their pocketbook. Nationalism is a sin. People are sheep. The agricultural revolution was the worst mistake in human history. Progress isn't all its cracked up to be.