The leader of radical Sunni fighters who have made rapid military advances in Iraq is the rising star of global jihad, driven, Islamist fighters say, by an unbending determination to fight for and establish a hard-line Islamic state.

Abu Bakr al-Baghdadi, commander of the Islamic State in Iraq and Syria (ISIS), now controls large parts of eastern Syria and western Iraq, a vast cross-border haven for militants in the Sunni Muslim core of the Middle East.

Despite his power — and a $10 million reward offered by the U.S. for information leading to his capture — little is known about a man who for his own survival has shunned the spotlight.