Yazid increased the caliphate and the law of inheritance that his father had enacted. He was not yet of age for this position because he was negligent of his duties. Al-Husayn ibn Ali and Abd Allah ibn al-Zubayr noted this and sought to prove it against him. They were in Medina, so Yazid sent to its governor to arrest them. He fled from there. Al-Husayn went to Iraq because the majority of his father's Shi'a were there, and a large party gathered around him in Kufa and elsewhere.

"The March of Husayn to Kufa" Al-Husayn received letters from the people of Kufa urging him to march to them to pledge allegiance. The governor at that time was Al-Nu'man ibn Bashir al-Ansari. So Husayn sent Muslim ibn Aqil ibn Abi Talib to Kufa to take their pledge. He arrived in Kufa, and it is said that thirty thousand people, or rather one hundred and twenty thousand people, pledged allegiance to him. Yazid was displeased with Al-Nu'man ibn Bashir, so he appointed Ubayd Allah ibn Ziyad, who was the governor of Basra, over Kufa. He came to Kufa and saw the state of the people. He admonished them and urged them to obey Yazid ibn Mu'awiyah. Muslim ibn Aqil remained as he was upon the arrival of Ubayd Allah ibn Ziyad. Then those who had pledged allegiance to Husayn gathered around Muslim ibn Aqil, and they besieged Ubayd Allah ibn Ziyad in his palace. There were no more than thirty men with Ubayd Allah in the palace. Then Ubayd Allah ordered his companions to watch from the palace and to call to obedience and discourage disobedience. A woman even came to her father and brother and said, "Go back, the people will suffice for you." So the people dispersed from Muslim, and only thirty men remained with Muslim. He was cornered and trapped. The herald of Ubayd Allah ibn Ziyad announced, "Whoever brings the head of Muslim ibn Aqil will receive a reward." So Muslim was captured and brought before Ubayd Allah. Ubayd Allah brought Muslim before him, insulted him, and insulted Husayn and Ali, and then struck off his neck at that hour. His body was thrown from the palace. Then Hani' ibn 'Urwah was brought. He was among those who had taken the pledge of allegiance to Husayn. His neck was also struck off, and his head was sent to Yazid ibn Mu'awiyah. The killing of Muslim ibn Aqil was on the eighth day of Dhu al-Hijjah in the year sixty. Husayn was in Mecca at the time, preparing to head to Iraq. Abd Allah ibn Abbas disliked Husayn's going to Iraq and advised him, saying, "Husayn, son of my uncle, I fear for you from the people of Iraq, for they are a treacherous people. Stay in this land, for you are the master of the Hijaz. If you must leave, then go to Yemen, for it has Shi'a who will protect you and its mountains and valleys." Al-Husayn said, "Son of my uncle, I know that you are advising me with sincerity and compassion. I have made up my mind." Then Ibn Abbas left him on the day of Tarwiyah in the year sixty, and Husayn left Mecca. A group of Arabs gathered around him. Then the news of the killing of Muslim ibn Aqil reached him, and the people abandoned him.