Juhayman al-Otaybi came from a prominent Najdi family - his grandfather had ridden with Ibn Saud in the Ikhwan, the very militia that helped build the Saudi state. Juhayman had been a corporal in the Saudi National Guard and a student of Sheikh Abd al-Aziz Ibn Baz, later Grand Mufti of Saudi Arabia. In the mid-1970s he turned on his teachers, accusing the royal family of building palaces while neglecting mosques and of courting Western alliances. In prison for sedition, he met his brother-in-law Muhammad Abdullah al-Qahtani. Juhayman claimed a vision from God: Qahtani was the Mahdi, the redeemer whose arrival would herald the end of days. The date - 1 Muharram 1400, the turn of an Islamic century - was chosen deliberately, tied to the tradition of the mujaddid, a renewer who appears at each century's turn.

Among the hostages were pilgrims from dozens of countries - people who had saved for years, in some cases whose entire villages had pooled funds to send them. Many were elderly. Some were children traveling with parents. The militants' initial assault killed worshippers and police alike. The first counter-attack by 100 Ministry of Interior officers was repulsed with heavy casualties. The Saudi government had a theological problem before it had a military one: Islamic law forbids violence within the Grand Mosque, and before any serious assault could be mounted, the ulama - the religious scholars, led by Juhayman's former teacher Ibn Baz - had to issue a fatwa permitting armed force. They did, but their language was "curiously restrained," the scholars calling the militants not apostates but only "the armed group."

The Saudis called Paris. France dispatched three commandos from the elite GIGN, who reportedly converted to Islam in a formal ceremony before approaching the holy city - non-Muslims are forbidden in Mecca. They brought a type of gas designed to dull aggression and obstruct breathing. Pakistani Special Service Group advisors also helped coordinate the response. The militants had hidden supplies in the hundreds of small underground chambers beneath the mosque, used as hermitages. The gas was pumped in; it got lost in the tunnels. With casualties mounting among Saudi troops and hostages alike, engineers drilled holes into the courtyard and dropped grenades into the chambers below. The strategy cleared the tunnels but killed hostages who had been herded there. Lawrence Wright, reconstructing the siege years later, described sharpshooters picking off the survivors as they surfaced.

The official toll was 255 killed - pilgrims, troops, and militants combined - with another 560 injured, though diplomats at the time believed the real number higher. Military casualties alone were 127 dead and 451 injured. Among the dead: Muhammad al-Qahtani, the declared Mahdi, killed in the retaking. Juhayman al-Otaybi was captured alive with 67 other insurgents. On 9 January 1980, 63 were publicly beheaded in the squares of eight Saudi cities - Riyadh, Mecca, Medina, Dammam, Buraidah, Abha, Ha'il, and Tabuk - chosen, as historian Sandra Mackey noted, to reach "other potential nests of discontent." The hostages who survived - many of them pilgrims who had come for the most peaceful of journeys - scattered back to dozens of countries, carrying trauma most never spoke publicly about.

Ayatollah Khomeini, in revolutionary Iran, told radio listeners the attack was "the work of criminal American imperialism and international Zionism." It was not true - the militants were Saudi Sunni millenarians, ideological opposites of Khomeini's Shia theocracy - but the rumor burned. The U.S. embassy in Islamabad was overrun and torched the next day; Tripoli's followed a week later. Inside Saudi Arabia, King Khalid's government turned inward. The religious police grew more assertive. Stricter Islamic law was enforced across the kingdom. Women's rights, modestly expanding through the 1970s, contracted. The Saudi state had survived the seizure, but it had absorbed the lesson that its legitimacy was religious before it was royal. Forty-six years on, you can fly over Mecca today - the coordinates below the mosque complex are 21.42 degrees north - and see a city transformed by tower cranes and expansion. The sanctuary itself, scrubbed of its blood, welcomes millions each year. The dead are still counted quietly, a name at a time.