When Abu Bakr al-Baghdadi took the reins of the Islamic State of Iraq in 2010, few had heard of the organization or its new leader, then an austere religious scholar with wire-frame glasses and no known aptitude for fighting and killing.
But just four years later, Mr. Baghdadi had helped transform his failing movement into one of the most notorious, vicious and — for a time — successful terrorist groups of modern times. Under his guidance, it would burst into the public consciousness as the Islamic State, an organization that would seize control of entire cities in Iraq and Syria and become a byword for shocking brutality.

He died Oct. 26 in northwest Syria, during a raid conducted by Special Operations forces, President Trump said in a Sunday morning news conference at the White House. Mr. Baghdadi was 48, and had run into a “dead-end tunnel” before he “ignited his vest,” killing himself and three of his children, Trump said.