Finally...

Finally, al-Husayn made use of Mu'awiya's mistakes such as his attacks against the peaceful Muslim cities, his attitude towards the conditions of the Peace Treaty of al-Hasan, his killing al-Hasan with poison, his pledge of allegiance to his son Yazid, and so on. All these errors of Mu'awiya, in addition to the support of the Muslim public opinion urged al-Husayn to take steps against the Umayyads.

In the meantime al-Husayn made us of the errors of Yazid, Mu'awiya's successor, who was fond of monkeys and wine. All these…