A lightning offensive saw Iraq’s second largest city, Mosul, fall to the insurgents. The pattern extended itself to Tikrit, farther south, then Samarra, and the battle spread to the oil refining center of Baiji. Most of this was first attributed to ISIS. The question was asked, then: Why and how could a well-armed force of 20,000 Iraqi troops, armed and trained by the U.S., dissolve in the face of 800 terrorists?
