Battles & Wars › Modern conflicts › War on Terror
Battle of Mosul (2016–2017)
October 17, 2016 – July 20, 2017· Battle· Middle East & Africa
Well documentedSolid records, physical evidence or scientific consensus.
A nine-month campaign by Iraqi forces, backed by US-led airstrikes, to retake Iraq's second city from the Islamic State.
See it on the Battles & Wars map →What happened
ISIS had seized Mosul in June 2014. From October 17, 2016, about 100,000 Iraqi soldiers, police, Kurdish Peshmerga and militia fighters attacked several thousand entrenched ISIS fighters. The east fell by January 2017; the dense old city in the west held out until July. ISIS used suicide car bombs, tunnels, human shields and small commercial drones dropping grenades. In June it blew up the al-Nuri mosque where its caliphate had been declared. Civilian deaths are estimated at 9,000 to 11,000 or more; estimates vary widely.
Why it matters
It broke the caliphate's hold on Iraq and became a textbook case of how costly modern city fighting is, above all for civilians.
How we know
Iraqi and coalition military records, an Associated Press investigation of morgue lists, Amnesty International and UN reports, and Airwars tallies of airstrike casualties.
Still debated
The true civilian toll, and how many died from coalition strikes versus ISIS, is disputed; one March 2017 US strike killed over 100 civilians in a single building.
Connections (2)
▸Battle of Mosul (2016–2017) broke the Iraqi stronghold of Islamic State (ISIS) territorial 'caliphate'Well documented
The connection
Mosul was the largest city ISIS held and the place where Abu Bakr al-Baghdadi proclaimed the caliphate in 2014. Its loss in July 2017, followed by Raqqa in October, stripped ISIS of its main sources of people, taxes and legitimacy; its last patch of territory fell in March 2019.
When and how
Mosul, northern Iraq, October 2016 to July 2017; Iraqi Prime Minister Haider al-Abadi declared victory on July 10, 2017.
How we know
Iraqi and coalition military records, ISIS administrative files captured in the city, and satellite imagery tracking the battle.
Debates and open questions
Whether the victory came at too high a civilian cost, and whether slow rebuilding of Mosul's old city leaves room for ISIS to return.
▸Battle of Mosul (2016–2017) was called the biggest urban battle since World War IIMostly agreed
The connection
Analysts compared Mosul to World War II city battles such as Stalingrad, Manila and Berlin: a large army fighting block by block for nine months through a city of over a million people, against defenders using tunnels, snipers and booby traps.
When and how
The comparison was made in 2017 by US commanders and analysts, including John Spencer of West Point's Modern War Institute.
How sure are we?
Troop numbers, length and destruction are documented; whether it was the biggest urban battle since 1945 depends on how size is measured.
Debates and open questions
Some point to Aleppo (2012–16), Grozny or, later, Mariupol (2022) as rivals; rankings depend on whether you count troops, civilians or damage.