(CNN) The head of ISIS, Abu Bakr al-Baghdadi, is dead. The man who led the state that called itself Islamic -- first capturing Raqqa in Syria and then leading a blitzkrieg through Iraq, rampaging through Mosul, Tikrit, to the gates of Baghdad -- is no more.

ISIS established a horrifying standard of brutality, re-establishing slavery, practicing what amounted to genocide against the Yazidis , carrying out mass executions and beheadings -- all caught on camera -- and demolishing religious sites and antiquities.

The United States, with the help of its coalition allies, Iraq and the Syrian Democratic Forces (SDF), destroyed the Islamic State and killed Baghdadi.

ISIS, however, is far from finished. It operates in West Africa, Libya, Egypt's Sinai Peninsula, Afghanistan and the Philippines, and has followers in Europe and elsewhere. That, in addition to as many as 18,000 fighters still on the loose between Syria and Iraq, according to a report issued by the Pentagon's Inspector General in August.

There is no reason to conclude that the threat from ISIS' far-flung network of affiliates and sympathizers has disappeared with the passing of Baghdadi. He may have excelled in his evil mission, but he was at the top of a pyramid of power and others will come forward to claim his mantle of leadership and perhaps learn from his demise.

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