Right before the fall of Ramadi, Iraqi forces were surrounded by ISIS fighters. ISIS came at them with 2 bulldozers rigged with explosives. The Iraqi forces numbered about 150 men spread out smaller units in Western Ramadi.
Near the end, the Iraqis call for air support and (wait for it) the air support never comes. The unit then runs out of ammunition and they are forced to withdraw. ISIS then takes the city of Ramadi
The Iraqi soldier interviewed by CNN's Arwa Damon says the ISIS fighters know that there is a lack of ammunition in the Iraqi units and when the firing stops, ISIS moves in.
Here's the video-----