From: Star Trek: The Original Series
Planet: Ekos. A humanoid race at war with a neighboring planet, Zeon. Ekosian society was based on World War II-era Nazi Germany on Earth due to a miscalculation by a Federation cultural observer named John Gill. His intention was to teach the Ekosians a pattern of government based on Nazi-like efficiency, but with more compassionate principles. His efforts failed when power corrupted those in charge.