Last week, a self-described heir to the Prophet Muhammad declared himself the supreme leader of a new Islamic state stretching from eastern Syria to northern Iraq. How did Abu Bakr al-Baghdadi, the nom de guerre of a mediocre Iraqi religious scholar in his mid-40s, outmaneuver al Qaeda as the new vanguard of jihadist ideology? How did he and his followers—armed with Kalashnikovs, smart phones and their ominous black banner—so suddenly take over the campaign to rid the Muslim world of Western and secular influence?
The rise of Mr. Baghdadi and his newly proclaimed “caliphate” highlights what had been a closely held secret of the Sunni jihadist movement: a split in the ranks that had been festering for years. It pits a new generation of shock troops hardened by battle in Iraq and Syria against al Qaeda veterans who had built the movement but were increasingly seen as too passive, both politically and theologically.