Ali's concession at the Battle of Siffin arouses the anger of a large group of his followers.

Disappointed with 'Ali's failure to insist on his right to rule, they protest, Qur (judgment) belongs to God alone; and believe that arbitration would be a repudiation of the Qur'anic dictum (49:9) "If one party rebels against the other, fight against that which rebels”.

A small number of these pietists (kharaju) withdraw to the village of Harura' under the leadership of Ibn Wahb and, when arbitration proves disastrous to 'Ali, are joined near Nahrawan by a larger group.

These Kharijites (”Seceders”), as they come to be known, are opposed equally to the claims of Ali and to those of Muawiyah.

...Husayn's at Karbala, about eighty kilometers southwest of Baghdad, are holy places of pilgrimage for Shias, many of whom feel that a pilgrimage to both sites is equal to a pilgrimage to Mecca.

The importance of these events in the history of Islam cannot be overemphasized.

They create the greatest of the Islamic schisms, between the party of Ali (the Shiat Ali, known in the West as Shias or Shiites) and the upholders of Muawiyah (the Ahl as Sunna, the People of the Sunna—those who follow Muhammad's custom and example) or the Sunnis.

The Sunnis believe they are the followers of orthodoxy.

The ascendancy of the Umayyads and the events at Karbala, in contrast, leads to a Shia Islam which, although similar to Sunni Islam in its basic tenets, maintains important doctrinal differences that have pervasive effects on the Shia world view.

Most notably, Shias viewed themselves as the opposition in Islam, the opponents of privilege and power.

They believe that after the death of Ali and the ascension of the "usurper" Umayyads to the caliphate, Islam took the wrong path; therefore, obedience to existing temporal authority is not obligatory.

Furthermore, in sacrificing his own life for a just cause, Husayn becomes the archetypal role model who inspires generations of Shias to fight for social equality and for economic justice.

Hussein, after receiving some favorable indications, sets out for Kufah from Mecca with a small band of relatives and followers.

According to traditional accounts, he meets the poet al-Farazdaq on the way and is told that the hearts of the Iraqis are for him, but their swords are for the Umayyads.

The governor of Iraq, on behalf of the caliph, sends four thousand men to arrest Hussein and his small band, trapping him on October 10 near the banks of the Euphrates River.

Hussein refuses to surrender, and he and his escort are slain, his head sent to Yazid in Damascus. (Shi'ite Muslims observe the first ten days of Muharram, the date of the battle according to the Islamic calendar, as days of lamentation in remembrance of Hussein's martyrdom.)

Revenge for Hussein’s death at the Battle of Karbala' is turned into a rallying cry that will help undermine the Umayyad caliphate and give impetus to the rise of a powerful Shi'ite movement, making permanent a division in Islam between the party of 'Ali and the Sunnite majority.

The Umayyads subdue Iraq, but rebellions in the name of this or that relative of 'Ali will continue, attracting more and more non-Arab support and introducing new dimensions to his cause.

...in Karbala', the shrine of al-Husayn ibn 'Ali, the first saint of the Shi'a Muslims, is razed, and further pilgrimages to the town are forbidden.

Suleiman agrees in return to allow Shi'ite Persian pilgrims to visit Mecca and Medina as well as their holy places in Iraq.

The Wahhabis capture and sack the Shi'ite holy city of Karbala' in the central region of Ottoman Iraq in 1801.