Although much has been written to explain the tactical military successes of the Islamic State (IS), there has not yet been a comprehensive assessment of how, since June 2014, IS has managed to rule over terrain larger than Lebanon to include 8 million Iraqis and Syrians.
How has it been possible that in a short three months IS has been able to control extensive terrain, with 3,000 IS fighters capturing Mosul, which was guarded by 30,000 Iraqi soldiers, and after seizing Mosul on June 10 engage in battles two days later with Iraqi forces in towns north of Baghdad, 230 miles from Mosul?