When the Abbasid Revolution overthrew the Umayyad Caliphate in 748-750, it rode to power on a promise. The slogan spoke of a chosen one from the Family of Muhammad who would rule justly and according to the Quran. Many thought this meant the Alids - descendants of the Prophet through his cousin Ali ibn Abi Talib and his daughter Fatima. But the Abbasids, descendants of the Prophet's uncle al-Abbas, claimed membership in the same wider family. They took the caliphate. The Alids got honors and stipends, and for many of them, prison. Husayn grew up in what one modern historian has called an atmosphere of extreme piety and secret hatred for the Abbasids. His father, Ali al-Abid, had voluntarily shared the imprisonment of Alid relatives and died in custody in 763. His mother Zaynab was a sister of Muhammad al-Nafs al-Zakiyya - the Alid who had led the last great Alid revolt two decades earlier.

In 785, the conciliatory caliph al-Mahdi died, replaced by his harsher successor al-Hadi. Husayn and his followers, planning a rising timed to the Hajj of 786 when thousands of Alid sympathizers would be in Mecca, had their hand forced by a confrontation in Medina. The Abbasid governor, al-Umari, had flogged three men - including a son of al-Nafs al-Zakiyya - for drinking wine. Then the son fled, having been vouched for by Husayn. Tempers broke. On the morning of 16 May, Husayn and about 26 supporters seized the Mosque of the Prophet. Dressed in white, Husayn took the pulpit. The muezzin was forced to pronounce the call to prayer in the Shia wording. Followers arrived and swore allegiance. Two Alids present refused to participate - one of them was Musa ibn Ja'far al-Kadhim, whom Twelver Shia consider the seventh imam, and who warned Husayn that this would end only in his death. The fighting that followed lasted eleven days. Husayn could not secure the city. On 28 May, with 300 followers, he marched for Mecca.

Al-Hadi appointed his uncle, Muhammad ibn Sulayman ibn Ali, to crush the revolt. Several Abbasid princes were already in Mecca, returning from that year's pilgrimage. Their armed retinues combined: 130 horsemen, 200 riders on donkeys, and unspecified infantry. After a show parade through Mecca, they encamped at Dhu Tuwa on the city's edge. Husayn and his men arrived on 11 June. The two armies met at the wadi of Fakhkh. The Alids focused their attack on the Abbasid left wing. Muhammad ibn Sulayman broke through on the right, then wheeled the right and center against the main Alid force - massed together, in Al-Tabari's phrase, as if they were a compact ball of spun thread. The Alids were routed. During the fighting, a pledge of clemency was offered; Husayn refused it and fought on until he was killed. Over a hundred of his followers fell beside him. Their bodies lay unburied at the battlefield for three days.

Some of the surrendered Alids were executed on the spot at Mecca. Al-Hadi executed at least three more in Baghdad. Medieval Muslim authors report stories of the caliph's sorrow over the necessity of killing the Prophet's offspring, but modern historians doubt those accounts - other sources record him ordering the executions himself. In Medina, al-Umari burned the houses of the Alids and confiscated their property. But many Alids escaped by mingling with the pilgrims returning from the Hajj. Two of them were brothers - Yahya ibn Abdallah and Idris. Yahya would later raise a revolt in Daylam, in northern Iran, in 792. Idris fled west across North Africa, and in 789 founded the Idrisid dynasty in what is now Morocco. The dynasty he established would rule for nearly two hundred years. The battle that was supposed to end Alid opposition instead scattered it across the Islamic world - from Morocco in the west to northern Iran in the east - carrying Alid loyalties to places Abbasid power could not reach.

The wadi of Fakhkh became known to Muslims as the Martyrs. Shia tradition preserved the memory of Husayn's stand carefully. The formula of the oath his followers swore to him - promising to defend the oppressed and redress injustices - echoed the earlier oath of Zayd ibn Ali in 740 and would be echoed again a century later, when al-Hadi ila'l-Haqq Yahya founded the Zaydi state in Yemen. During his brief rising in Medina, Husayn had promised liberty to enslaved people who joined him. Faced with their masters' protests that this was unlawful, he was forced to return some of them - a small and telling detail about the limits of what a rebel could actually deliver in 786. The revolt failed. But it entered a long tradition of Alid resistance that would outlast the caliphate that crushed it. The wadi is no longer a place outside Mecca - the modern city has long since grown over it. The name Fakhkh survives in memory and in prayer.