Mu'awiya began a campaign to introduce Monarchy into the structure of Islam. To have Monarchy, by force or otherwise is alien to Islam, an innovation in religion, simply not acceptable. Everyone knew that, for Islam does not subscribe to any form of Royalty through inheritance or Monarchy. In Islam it is supposed to be Shura.
Nevertheless, Mu'awiya sent his agents to the prominent members of the communities to obtain allegiance of loyalty to his son Yazid. But Yazid was evil, of the drinking type, incompetent, contemptible, and a pleasure-seeking person. People knew that. So the people protested vigorously. There was anger everywhere. Emotions went sky high. To calm people down, at least temporarily, Mu'awiya decided to send his son Yazid to Mecca for the pilgrimage. Yes, Yazid did go to Mecca but only after taking alcohol with him as well as a chorus of girls for his entertainment.