Why did the mormon faith come under new attack while they were settled in nauvoo, illinois? why did the mormons eventually leave?

As a morman or member of the church of Jesus Christ and latter day saints i can tell you

in nauvoo is where Joseph smith was teaching the word of god and some people did not like that he was there so they tared and feathered him but they still did not leave but when he had a talk with God through prayer he said go to Missouri 

so the answer  is Joseph was preaching and the other people did not like it and god said to leave