Units with the reform ability can reform a city, which causes 5 unhappiness while removing conversion. Reforming costs 1,000 gold.
Great Library entry[]
There is a long tradition of governments or religions using oppressive techniques to crush opposition, particularly religious opposition. One of the most famous crackdowns, The Spanish Inquisition (which actually swept most of Europe), forced people through often brutal means to bow before the power of the Catholic church. However, this is by no means the only time such oppression has occurred. In the Islamic as in the Communist worlds, governments have often resorted to brutal tactics to either oust or force into submission those of differing beliefs.