Five years on: lessons learnt by the US military during Mosul's liberation

The US-led Operation Inherent Resolve was instrumental in defeating ISIS

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  An Iraqi federal policeman fires a machine gun at an ISIS position on a nearby rooftop during fighting in west Mosul in April 2017. Getty Images

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  Iraqi troops patrol areas retaken from ISIS in western Mosul on March 9, 2017. AFP

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  Iraqi forces fighting to retake Mosul airport from ISIS fire a missile from a rocket launcher on February 23, 2017. Florian Neuhof / The National

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  An Iraqi soldier sprays fire at an ISIS position across the road in west Mosul. Florian Neuhof / The National

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  Iraqi army personnel check ammunition during clashes with ISIS militants north of Mosul on December 29, 2016. Reuters

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  Members of an Iraqi special forces police unit fire at ISIS. Reuters

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  A member of the Iraqi special forces runs for cover. Reuters

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  Iraqi families escape the fighting in a bullet-strewn vehicle outside Mosul. AFP

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  Iraqi families seen near Qayyarah, outside Mosul. AFP

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  Popular Mobilisation Forces (PMF) personnel fire artillery rounds. Reuters

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  An Iraqi air force helicopter fires missiles at ISIS targets. Reuters

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  Iraqi tanks advance towards ISIS positions in the Old City in western Mosul on June 18, 2017. Reuters

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  An image grab taken from an ISIS propaganda video shows Abu Bakr Al Baghdadi addressing worshippers at a mosque in Mosul in 2014. AFP

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  An Iraqi special forces soldier looks down the entrance of a tunnel used by ISIS fighters inside a restaurant in Bazwaya, east of Mosul. Reuters

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  Displaced Iraqis flee their homes in western Mosul. Reuters

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  Children play in Qayyara, outside Mosul, where ISIS fighters set fire to crude oil fields as they retreated in October 2016. Photo: Alessio Romenzi

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  An Iraqi army soldier gestures above an accused ISIS member who tried to flee Mosul on October 31, 2016. Photo: Alessio Romenzi

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  Al Nuri Mosque in Mosul, destroyed by ISIS, is being rebuilt with assistance from the UAE. Reuters

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  A man cries as he carries his daughter while walking from an ISIS-controlled part of Mosul towards Iraqi special forces during a battle in Mosul, Iraq, March 4, 2017. Reuters

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  ISIS militants firing automatic weapons during a firefight outside Mosul, near Nineveh, Iraq.

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  A view of Al Nuri Mosque in Mosul, Iraq, where ISIS declared a caliphate in 2014. Photo: Gus Palmer / Keo Films / Handout

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  Iraqi security forces take part in an operation against ISIS in Al Shura, south of Mosul. Reuters

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  Iraqi Counter-Terrorism Service making the victory gesture as members hold the black ISIS flag upside down outside the destroyed Al Nuri Mosque in the Old City of Mosul after the area was retaken. AFP

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  An Iraqi forces sniper looks on as smoke billows following an air strike by US-led international coalition forces fighting ISIS in the Old City of Mosul on July 9, 2017. AFP

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  A mass grave of ISIS victims in Mosul. AP

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  Iraqi soldiers take cover during clashes with ISIS in Mosul. Reuters

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  Counter-terrorism service troops advance towards Ghozlani military complex, south of Mosul, on February 23, 2017. Reuters

After nine gruelling months of street-to-street fighting and near-continuous aerial bombardment, Iraqi forces in July 2017 wrested control of Mosul, Iraq's second-largest city, from the brutal hands of ISIS.

Months in the making, the victory could not have come when it did without intense support from a US-led coalition that helped to arm, train and equip Iraqi soldiers.

It also provided key information and air support to the local forces that only three years earlier had been humiliated by the speed and scope of the ISIS advance.

Mosul's liberation stands as a watershed moment in the fight against ISIS and signalled the start of the end for the terror group that at its peak in 2014 controlled about one third of Syria and Iraq, murderously governing a territory almost the size of England.

“The writing was on the wall that the so called caliphate's days were numbered,” said Nathan Sales of the Atlantic Council, who served as co-ordinator for counter-terrorism and the special envoy to the global coalition to defeat ISIS under former president Donald Trump.

Mr Sales, who began that role a month after the battle of Mosul ended, said it was a time of optimism in Iraq and in the Trump administration.

“With Iraq’s second-largest city now having been liberated and in friendly hands, it was only a matter of time before the campaign ended in the total defeat of the so-called ISIS caliphate,” he told The National.

For three years, the black-and-white ISIS flag flew over Mosul, a city of more than 1.6 million people in Nineveh province, whose rich history is deeply intertwined with that of the region.

It was perhaps the clearest indication of just how serious a threat the group posed to the region and to the world.

In 2014, Abu Bakr Al Baghdadi declared a "caliphate" from the lecturn of the Great Mosque of Al Nuri, a renowned centre of worship, whose leaning minaret was long a symbol for the city.

ISIS would later destroy the structure, along with much of the Old City, during the battle of Mosul.

The fight to liberate the city took nearly a year of planning, vicious fighting and the support of dozens of countries.

The US-led military coalition, called Operation Inherent Resolve, had the task of eradicating the terror group, but was hesitant to put too many boots on the ground after the US had withdrawn its forces in 2011 at the end of the Iraq War.

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  Members of a demining squad take part in an operation to clear mines planted by ISIS militants in the Old City of Mosul, Iraq. All photos: Reuters

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  A member of a demining squad gives directions during an operation to clear mines in the Old City of Mosul.

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  Members of a demining squad take part in an operation to clear mines in the Old City of Mosul.

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  A member of a demining squad takes part in an operation to clear mines in the Old City of Mosul.

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  A member of a demining squad takes part in an operation to clear mines in the Old City of Mosul.

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  A member of a demining squad takes part in an operation to clear mines in the Old City of Mosul.

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  A member of a demining squad takes part in an operation to clear mines in the Old City of Mosul.

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  A member of a demining squad takes part in an operation to clear mines in the Old City of Mosul.

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  A member of a demining squad writes the word 'safe' on a wall.

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  A member of a demining squad walks down a street during an operation to clear mines planted by ISIS militants in the Old City of Mosul.

“We had to come up with a way to help the Iraqis without a significant ground force,” a retired US army colonel, who worked with the operation in Baghdad at the peak of the anti-ISIS fight, told The National.

The coalition decided to focus on "the use of air power and the use of advisers to both train and retrain the Iraqi army to get them up to a level where they could take back some of the cities that they lost to ISIS".

Starting in the autumn of 2016, Iraqi forces with the help of Kurdish Peshmerga and coalition air support gradually started to take villages surrounding Mosul.

By the summer of 2017, the fight was fully in the ancient city, leading to intense urban warfare.

“It was hard work and complex,” the colonel recalled.

“It required synchronising air power, ground power, and engineering equipment to clear away rubble and to reduce obstacles.”

American soldiers are seen at the US army base in Qayyara, south of Mosul, on October 25, 2016. Reuters

The job was made more difficult by the presence of civilians in the city, a concern ISIS did not share.

“It was a huge factor, ISIS was in and amongst the population,” said the retired colonel, who praised the coalition's ability to use “precise” air strikes against the enemy.

“I don't think there has ever been a more precise air campaign."

But thousands of civilians were killed or wounded in Mosul during the intense fighting that reduced much of the city to rubble. Some of these deaths were caused by US and coalition air strikes.

After more than nine months of fighting, the Iraqi army finally reclaimed the city.

It was a huge blow to ISIS, whose territorial decline increased rapidly in the following months, ending in their final loss in Baghouz, Syria, in March 2019.

The liberation of Mosul proved that the US Army and coalition forces could be successful even without their own troop there, said Maj Thomas Arnold, a US army strategist who studied the battle of Mosul.

“What we learnt is that we can keep people in the field as long as they're willing to fight," Mr Arnold said.

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  Foreign tourists walk inside Mosul's Old City in Iraq after the city's liberation from the Islamic State group. All photos: Reuters

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  Mosul is the second-largest city in Iraq.

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  The city was liberated in 2017 after three years under the Islamic State's rule.

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  The occupation left Mosul, especially its Old City, in ruins and its people displaced.

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  Iraq now issues visas on arrival for several nationalities to boost tourism.

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  Visitors in Mosul are introduced to the city's heritage and marketplaces.

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  Tourists walk inside the Old City.

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  The 800-year-old Al Nuri mosque and its leaning minaret are being rebuilt thanks to a joint project by the UAE and Unesco.

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  Tourists look at the archaeological artefacts from Al Nuri mosque.

Mr Arnold, who spoke to The National in a personal capacity and whose views do not represent the US Army, believes that the US has carried over some of the lessons learnt in its support of the Iraqi army against ISIS to the war in Ukraine and its support of the Ukrainian military.

He said that while there was no official coalition supporting Ukraine, the US and other Nato countries stepped up to ensure Ukrainians had the tools and equipment needed to defend themselves, something the coalition forces also did for the Iraqi.

Mr Sales agreed. “The strategy of empowering motivated local partners worked very well in Iraq, worked very well in Syria. It’s working in Ukraine."

But the strategy is by no means a guarantee of success.

The Taliban last year prevailed in a 20-year conflict with western-backed Afghan security forces, who in many instances suffered from poor morale and a lack of basic weapons and provisions, as corruption swept the ranks.