He gained enough respect that by 2010, after several leaders of al-Qaeda in Iraq were killed, he assumed control of the group. At that time, the power of that Islamic militancy in Iraq was at its lowest ebb, and the number of killings had plunged. The Sunni rebellion, which it had once spearheaded, was on the verge of collapse.

But then Syria happened. The civil war there, which left a vacuum of authority in large tracts of country, fueled a resurgence of the group. The upheaval gave rise to the Islamic State of Iraq and Syria (ISIS). Over the following years, as many as 12,000 militant Islamists — 3,000 of whom were from Western countries — flocked to the region to fight, according to the Soufan Group, an intelligence organization.

But even then, al-Baghdadi, today respected among militants as a battlefield tactician, maintained his anonymity. No one knows where he is, it is said. And reports say that on the rare circumstances he meets a prisoner, he wears a mask.

The rise of ISIS underneath his stewardship has been less about cult of personality, than what one expert told AFP signaled a “transnational ideology.”