The events of the Day of Ashura are the events happened for Imam al-Husayn (a) and his family, in the battle with the army of Yazid b. Mu'awiya led by 'Umar b. Sa'd on Muharram 10, 61/October 13, 680 in the land of Karbala which led to the martyrdom of Imam al-Husayn (a), his companions and his relatives. The rest of his caravan were also taken as captives.
Imam al-Husayn (a) considered the caliphate of Yazid illegitimate and for the first time expressed his objection to it in Mina after Mu'awiya began asking people to make allegiance to Yazid in 59/679. However, Imam al-Husayn's (a) movement began by his refusal to make allegiance to the governor of Medina as the representative of Yazid, and leaving Medina in 60/680. Imam (a) then went to Mecca. In Mecca, the Imam (a) received many letters from the people of Kufa who invited him for government of Iraq and promised that would support him. After some months staying in Mecca and before beginning of the rituals of Hajj, the Imam (a) went towards Iraq. Before he (a) arrived in Kufa, agents of 'Ubayd Allah b. Ziyad stood against the caravan of Imam (a) in Karbala. The siege of Imam (a) lasted some days and eventually led to the events of Ashura.