The Iraqi Army then began conducting an offensive into Anbar, in an attempt to bring the region back under government control. However, ISIL had made territorial advances in neighboring Syria , giving them access to more weapons  and substantially strengthening their position. ISIL named the military operation that resulted in their seizure of Mosul, "Bilawi Vengeance", a reference to their late commander's alias. Al-Bilawi blew himself up, and Gharawi hoped it would prevent an attack.
Though Mosul's first line of defense was thought to contain 2, soldiers, Gharawi says that "reality was closer to ". He noted that since all of the city's tanks were being used by Iraqi forces in the Anbar province , the city was left with little to combat the ISIL fighters.
The insurgents hanged, burned, and crucified some Iraqi soldiers during their attack. In the southern part of the city, five suicide bombers blasted an arsenal. The ISIL forces in the city totaled 1, militants, outnumbered by Iraqi forces by more than 15 to 1. After the attacks, most of the fighters either retreated into the desert or camouflaged among the local population. Sleeper cells hidden within the city were then activated and according to police, "neighbourhoods rallied to them".
Lacking plans and ammunition, Gharawi ordered the Iraqi military to retreat on the advice of retired general Khaled al-Obeidi. Iraqi Army soldiers fled the city while it was under attack, allowing the militants to control much of Mosul by midday on 10 June. There were reports that the group was advancing from Mosul to Kirkuk at the time. While capturing the city, the group freed nearly 1, prisoners, some of whom were greeted by the fighters. The militants, who were travelling in a group of around 60 vehicles, also took control of the Baiji prison and freed all the inmates within.
Local residents told members of the media that ISIL sent a group of local tribal chiefs ahead of them, trying to convince the guards at the oil plant to withdraw. Soldiers and police were also warned to leave the area. Reports suggested that the abducted were taken to a nearby militant base and were unharmed.
The attack came a day after 28 Turkish truck drivers were abducted by militants while delivering fuel to a power plant in Mosul. Local officials reported that checkpoints had been set up around the city, and that at least inmates had been freed from the city's prisons, many of them serving sentences under terrorism charges.
The government also spoke of a plan to reorganize its military, involving a collaboration between tribal people and the U.