Instead, the Iraqi Security Forces (ISF) collapsed, ISIS pushed their advantage, and large swaths of northern Iraq fell under the group's control, according to a special report from Reuters by Ned Parker, Isabel Coles, and Raheem Salman.
The report, compiled from months of research and interviews with ISIS-affiliated contacts, members of the Iraqi military, and Kurdish officials, re-creates the slow moving disaster that ended with the jihadist seizure of Iraq's second-largest city.
As it turns out, one of the main reasons for the fall of Mosul was the Iraqi Security Forces' fatally poor logistics.
The first line of Mosul's defence was the sixth brigade of the Third Iraqi army division. On paper, the brigade had 2,500 men. The reality was closer to 500. The brigade was also short of weapons and ammunition, according to one non-commissioned officer. Infantry, armor and tanks had been shifted to Anbar, where more than 6,000 soldiers had been killed and another 12,000 had deserted. It left Mosul with virtually no tanks and a shortage of artillery[.]
This shortage sharply undercut the manpower required to defend Mosul.
The city was meant to have approximately 25,000 soldiers and police defending it in total. In actuality, there was at most 10,000 security personnel in the city at the time of the attack.
And of these 10,000 personnel, many were under-equipped or deployed in a way that left the city badly exposed. One of the main entries into Mosul that ISIS attacked had only 40 men guarding it, according to the report.
Even when there enough personnel in place to put up resistance to the ISIS militants, the soldiers in Mosul found themselves outgunned.
"In my entire battalion we have one machine gun. In each pickup they had one," Dhiyab Ahmed al-Assi al-Obeidi, the colonel of the fourth battalion in Mosul, told Reuters.
Along with this logistical chaos, Reuters discovered that political failings played a decisive role in the fall of Mosul. On June 7, during the second day of the ISIS assault, Kurdistan President Massoud Barzani offered to send Peshmerga fighters to aid the ISF in Mosul. Maliki, suspicious of Kurdish intentions, twice declined the Kurds' assistance.
On June 10, Mosul fell to a force of slightly over 2,000 ISIS fighters as the final remnants of the ISF withdrew from the city, at times burning their uniforms in an attempt to blend in with the civilian population.
The fall of Mosul has led to a domino effect of instability throughout the rest of Iraq and the Middle East. ISIS fighters seized critical weapons from the ISF's bases in Mosul, which the jihadists then used to push their advantage further into both Syria and western and northern Iraq.