On Ashura in 680, Husayn, grandson of the Prophet Muhammad and the third imam of Shiite Islam, was killed during the battle of Karbala (in present-day Iraq), which opposed supporters of Husayn to those of Yazid I, the Umayyad caliph. The battle and Husayn's death is one of the founding schisms between Shiites and Sunnis. To Shiites, Husayn's death is equivalent to the way Christians view Christ's passion and death--a supreme act of suffering and redemption.
Husayn's death in Shiites' eyes is an event locked neither in time nor in place, but reflective of any Shiite community that considers itself oppressed, persecuted or humiliated. In the early days of the Iranian revolution in 1979, and again during the Iran-Iraq war a frequent slogan in Iranian streets and on Iranian broadcasts read, "Every day is Ashura, every place is Karbala, every month is Muharram."
Today, Ashura is commemorated by Shiites in the form of a ritualistically graphic, violent and bloody celebration of martyrdom as the faithful recreate Husayn's suffering by weeping, wailing, whipping and beating themselves, both to humble oneself in solidarity with the suffering and downtrodden and to help one's cause on the Day of Judgment.
Before Husayn's death, Ashura was for Muslims a day of joyous celebration as it commemorated, with Jews, Noah's landing of the Ark and the day Egypt let Moses and his people go.