THE SITUATION AT THE TIME OF MU'AWIYAH'S DEATH
Imam al-Husayn attained the Imamate in 50 A.H. after the death of his brother Imam al-Hasan. Imam al-Husayn's Imamate extended for ten years, of which nine years and four months coincided with Mu'awiyah ibn Abi Sufyan's Caliphate and approximately six months with the Caliphate of his son Yazid
Mu'awiyah died in 60 A.H. after twenty years as the Caliph. Contrary to the terms of the treaty made with Imam al-Hasan, in which he promised not to appoint a successor, Mu'awiyah formally named Yazid as heir to the Caliphate. Mu'awiyah had secured allegiance for Yazid from the majority of the Muslims apart from a few renowned personalities of the day, among whom were Imam al-Husayn, 'Abd Allah ibn 'Umar, 'Abd Allah ibn Zubayr and 'Abd al-Rahman ibn Abi Bakr. However, 'Abd al-Rahman ibn Abi Bakr died before Mu'awiyah.
MU'AWIYAH'S LAST WILL TO YAZID
The fear and concern that Mu'awiyah had because these individuals had not paid allegiance to Yazid is demonstrated in his last will to Yazid, written as he approached his death. He said to Yazid: "I have taken allegiance for your Caliphate from all the Muslims except for three people: al-Husayn ibn 'Ali, 'Abd Allah ibn 'Umar and 'Abd Allah ibn Zubayr. As for 'Abd Allah ibn 'Umar, treat him well and you will find him an ally. As for 'Abd Allah ibn Zubayr, find him, kill him and cut him into pieces, because, at the first opportune moment, he will search you out and tear you apart like a hungry lion or trick you like a fox. As for al-Husayn ibn 'Ali, the people of Iraq will only support his claim if they can persuade him to come out in revolt. If he does come out in revolt against you, overcome him in battle. However, you should not be hostile towards him because of his close family relationship with you and his great rights.
YAZID'S LETTER TO HIS GOVERNOR IN MEDINAH
After the death of Mu'awiyah, Yazid dispatched a letter to the governor of Medina, Walid ibn 'Utbah ibn Abi Sufyan, who was also his cousin. In the letter, he wrote: "O Walid! Extract the pledge of allegiance from al-Husayn ibn 'Ali without delay and under no circumstances allow him respite."
Walid, acting in accordance with the instructions, sent for Imam al-Husayn in the middle of the night. Imam al-Husayn, surmising