There’s a New York Review of Books article I quoted in another thread which discusses their support for local services. A later article in that journal questioned that characterization.
Recall that ISIS rules certain regions of Syria. They collect taxes. They collect utility charges. The Assad regime (who run Syria) let them do that so they can point to a Big Bad: see? Stick with us: the other choice is those guys . ISIS also controls certain oil regions in Syria, and now Iraq. They regulate the price and quality of goods in their territory.
So the Iraqi Army was going up against something like governmental army. That’s not to say that they were invincible: the Kurds have held them off on the border of Turkey for a while. But ISIS isn’t a guerilla army; they are led by some of Saddam’s old generals for instance.How ISIS Rules | Sarah Birke | The New York Review of Books
How ISIS was formed:
A cache of documents were found in a ISIS Syrian safe house, whose resident was killed in a firefight. They discuss the coalition between Islamicists and Iraqi military men that makes up ISIS.
The new reveal is that ISIS was created by Saddam’s former men. They provided military strategy. They chose the guy who would be the self-proclaimed caliph. They had deep ties to Syrian intelligence, which allowed them to form an uneasy partnership with Assad’s regime, where they would focus their efforts on common enemies.
They had knowledge of running a totalitarian state: that’s no small thing. The generals’ goal was to use ISIS as a method of taking over Iraq and re-establishing the old regime.
[INDENT]"But the invasion made this falsehood true… One of America’s first decisions on taking Iraq-- a terrible mistake that has halted the region ever sense-- was to disband Iraq’s enormous army, leaving its officers and soldiers with no income… “bitter and unemployed”. [/INDENT]The secret plot behind the creation of ISIS | Vox