Out of the 16,000 men who enlisted, 4,000 mobilized for the fight. In November 684, the Tawwabin left to confront the Umayyads, after mourning for a day at Husayn's grave in Karbala.
Calling themselves the "Tawwabin" (Penitents), they remained underground while the Umayyads controlled Iraq. After caliph Yazid's death and the subsequent ouster of Ibn Ziyad, the Tawwabin openly called for avenging Husayn's slaying.