Fall of Mosul

Overview

The fall of Mosul was the Islamic State’s capture of Mosul, Iraq’s second-largest city, on 10 June 2014. An assault that surged into western Mosul on 6 June overwhelmed its defenders in about 48 hours and opened a wider campaign across the Nineveh Plains. The event marked the beginning of Islamic State rule in the city. It is distinct from the Battle of Mosul (2016–2017), which ended that rule three years later.

Mosul’s loss plunged Iraq into a national security crisis. Army and Federal Police formations assigned to the city and surrounding province disintegrated, while the Islamic State gained a major urban stronghold. The collapse also transformed the security situation of the neighboring Kurdistan Region: Peshmerga forces moved to secure territory, including parts of Mosul east of the Tigris. Although the advance raised fears for Baghdad, the capital’s much larger, predominantly Shia population and concentration of regular forces and militias made a repetition of Mosul’s collapse unlikely.

Background

Mosul was an informal political and economic capital of Sunni Iraq. Parliamentary speaker Osama Nujaifi and his brother, Nineveh governor Atheel Nujaifi, were prominent residents and senior Sunni politicians. The city had also long served as a logistical and fundraising center for Al-Qaeda in Iraq and its successor, the Islamic State. Covert networks and access to militant safe havens in Syria and Iraq’s western desert helped the group prepare its 2014 assault.

Iraqi security-force weakness preceded the attack. Cohesion and manpower began declining as U.S. funding and mentoring ebbed in 2009. The deterioration accelerated after the Islamic State captured Fallujah in late December 2013. Before Mosul fell, Iraqi security forces still operated about 100 brigades across the army, Federal Police, border forces and special forces, but many were severely understrength. Absenteeism left some brigades with roughly 2,000 personnel instead of their nominal 4,000. The Mosul defeat therefore struck a force whose readiness had already been eroded over several years.

The city’s political position complicated its defense. Federal authorities and the Kurdistan Regional Government had unresolved disputes over security, oil sales and revenue. Islamic State attacks along the line between federal and Peshmerga forces exploited those tensions. Mosul’s proximity to Erbil also meant that its capture directly threatened security in the Kurdistan Region and made cooperation between Baghdad and Kurdish leaders urgent.

Course of the war

On 6 June 2014, Islamic State forces surged into Mosul’s western suburbs from approaches near their desert and Syrian safe havens. Three days of increasingly heavy fighting in western Mosul gave the attackers psychological dominance over Iraqi security forces. By 9 June, militants had overrun provincial government offices, security facilities, television stations and the airport. The collapse of Iraqi divisions defending Mosul and the surrounding Nineveh Plains allowed the Islamic State to take the city on 10 June.

The scale of the rout was severe but did not erase Iraq’s armed forces. Nineteen Iraqi army brigades and six Federal Police brigades disintegrated in June 2014. The losses included both Nineveh-based army divisions and Mosul’s entire 3rd Federal Police division. Panic after Mosul fell brought down roughly one-quarter of Iraq’s remaining active security forces. At the same time, 36 Iraqi army brigades and 24 Federal Police brigades survived. These figures show both the magnitude of the defeat and the forces still available for Iraq’s defense and eventual counteroffensive.

During the crisis, Peshmerga forces secured areas of Mosul east of the Tigris and established control in other territories as federal positions collapsed. The Islamic State’s capture of Mosul changed the Kurdistan Region’s security situation almost immediately. Retaking the western part of the city would require Baghdad to coordinate with Kurdish forces, while disagreements over oil marketing and revenue sharing remained obstacles. Recovery of Mosul became a test of leadership for caretaker prime minister Nouri al-Maliki as he sought reappointment.

The consequences spread beyond Nineveh. Mosul’s fall opened a route of advance toward Baghdad, and the Islamic State’s murder of more than 1,000 Shiite Iraqi cadets at Camp Speicher on 12 June deepened the crisis. Ali al-Sistani called young men to arms against the Islamic State. Iraq subsequently rebuilt its campaign against the group. Iraqi forces liberated Fallujah in June 2016 before turning toward Mosul, which remained one of the Islamic State’s most important strongholds.

Terrorist tactics and propaganda

The Islamic State combined rapid offensive movement with intimidation and an established underground network in Mosul. Its success in June 2014 depended in part on the defenders’ loss of morale during the fighting in the city’s west. During the later campaign to retake Mosul, the group relied heavily on suicide bombings to defend its positions. It claimed 501 such bombings in and around the city between October 2016 and late June 2017. Of 527 suicide bombings it claimed across Iraq and Syria during the first part of 2017, 265 were in Nineveh province.

Mosul also had symbolic importance for Islamic State propaganda. Abu Bakr al-Baghdadi chose the city for a speech presenting the group’s claimed caliphate. After Iraqi forces retook Mosul, Islamic State messaging denied that the battle had been decided and portrayed its fighters’ resistance as a success despite the loss of the city. The group urged supporters to attack targets in Turkey, Egypt, Tunisia and Western countries. Supporters later used the city’s fall and years under Islamic State rule in War and Media, a propaganda response to the film Mosul.

Outcome

The campaign to retake Mosul began in mid-October 2016. Iraqi forces, supported by the U.S.-led coalition, fought through the city over nine months. By early June 2017, they were retaking neighborhoods in western Mosul, while the Old City had become the Islamic State’s last major stronghold there. Fighting in Al-Zanjili, north of the Old City, was especially intense; Iraqi forces had retaken about one-third of that neighborhood in early June. The final battle in the Old City cost lives and destroyed parts of its dense urban fabric. Iraqi forces recaptured Mosul in July 2017.

As victory approached in late June, Prime Minister Haider al-Abadi described Mosul’s fall as the end of the Islamic State’s state-building project. The city’s recapture was a decisive blow to the group’s territorial rule and its ability to present itself as a functioning state. Its governance-related media output fell by 66 percent after July 2017, and it did not restore governance in Mosul. Control of the city had once given the group a major population center, a source of resources and a symbol of its ambitions; losing it removed all three.

Military victory in Mosul did not end Islamic State activity. The group continued attacks in Iraq, retained fighters and pursued limited governance in some areas. It still controlled Iraqi territory around Tal Afar, west of Mosul, after losing the city. Rival forces also sought positions along the Iraq–Syria border as Mosul’s recapture approached, including Popular Mobilization Forces advancing toward Al-Qaim. The contest over those routes showed that the wider war would continue beyond the city.

Aftermath and legacy

The nine-month recapture campaign displaced roughly one million people. By late July 2017, more than 830,000 Mosul residents had yet to return home. Those who did return went mainly to the less-damaged eastern part of the city. Destroyed homes created a housing shortage, while damage to water infrastructure disrupted supply. Generators provided temporary electricity. Iraqi security forces removed booby traps, mines and weapons left by the Islamic State, making clearance of explosive hazards part of the city’s recovery.

Mosul’s recapture weakened the Islamic State’s capacity to govern territory, yet its surviving networks remained capable of insurgent and terrorist attacks. Losses in Iraq and Syria also heightened concern that foreign fighters would move to other countries or to remaining strongholds. The fall of Mosul in 2014 thus stands as both a demonstration of how quickly a weakened security force could collapse and the event that set the stage for a prolonged campaign to reverse the Islamic State’s gains. The 2017 victory ended its rule in Mosul, while leaving Iraq to confront the destruction of the city and the group’s continuing activity elsewhere.