As Islamists gain ground in the fight against Syrian President Bashar Assad, the radical Nusra Front has emerged at the forefront, yet little is known about the group aside from its power and its affiliation with Al-Qaeda. Despite the mystery – leader Abu Mohammad al-Julani is never seen in public – those acquainted with the Nusra Front paint a picture of a highly organized group known for the discipline of its fighters and well-liked by the people in the territory it controls. The military leader of the Salafist Al-Islam Brigade, a sharp-witted man in his 40s who goes by the...