On 4 June, Iraqi police, under the command of Lieutenant General
Mahdi al-Gharrawi, cornered ISIL military leader
Abu Abdulrahman al-Bilawi near Mosul, in Iraq. Al-Bilawi blew himself up, and Gharawi hoped it would prevent an attack. At 2:30 in morning, ISIL convoys of pickup trucks, each truck carrying four fighters, entered Mosul by shooting at the city's checkpoints. Though Mosul's first line of defense was thought to contain 2,500 soldiers, Gharawi says that "reality was closer to 500". He noted that since all of the city's tanks were being used by Iraqi forces in
Al Anbar Governorate, the city was left with little to combat the ISIL fighters. The insurgents hanged, burned, and crucified some Iraqi soldiers during their attack. The government used helicopters to bomb the militants. In the southern part of the city, five suicide bombers blasted an arsenal. On 6 June ISIL began their attack on the northwestern part of the city. The ISIL forces in the city totaled 1,500 militants, outnumbered by Iraqi forces by more than 15 to 1. Two suicide bomber cars exploded, in Muwaffakiya, a village near Mosul, killing six
Shabak soldiers. After the attacks, most of the fighters either retreated into the desert or camouflaged among the local population. That day, about a hundred vehicles entered Mosul, carrying at least four hundred men.
Sleeper cells hidden within the city were then activated and according to police, "neighbourhoods rallied to them". The group also bombed a police station in the neighborhood of al-Uraybi, and encircled an abandoned building on the west of
Tigris River being used as a headquarters for a group of thirty police officers. According to
CBS News, ISIL fighters armed with machine guns and rocket-propelled grenades stormed the
Nineveh provincial headquarters that same day. The militants seized numerous facilities, including
Mosul International Airport, which had served as a hub for the U.S. military in the region. Militants captured the helicopters present at the airport, in addition to "several villages" and a military airbase in south
Saladin Governorate. The Iraqi army "crumbled in the face of the militant assault", which is evidenced by the fact that soldiers abandoned their weapons and dressed as civilians to blend in with the noncombatants.
Black flags were also flown over government buildings. ==Aftermath==