Hussain was grandson of Last Prophet Muhammad PBUH, after death of Muawiya r.a, Yazid took caliphate over and Hussain a.s was forced to allegiance of Yazid. All Muslims at that time knew that Yazid is an immoral and drinker and so called Muslim. He was not able to take over caliphate. Hussain a.s and many other companions and sons of companions did not allegiance of Yazid. At Last Hussain a.s went to Kufa, on way army of Yazid martyred Hussain a.s, his companions and many family members of Prophet pbuh. Head of Hussain a.s separated from body and was sent to Syria for Yazid, where on the way many miracles displayed due to head of Hussain a.s.