The Battle for Mosul (as it will undoubtedly be known once historians write their books) finally began in earnest in the early hours of October 17 after months of shaping operations around the capital of Nineveh Governorate.
Mosul is one of Iraq's most historically significant cities that has been the de facto capital of the Islamic State of Iraq and the Levant (ISIL, also known as ISIS) organisation for more than two years, and this battle is of strategic and also symbolic importance.
However, none should expect it to be quick, easy or even without enormous cost.
Iraqi battlefield track record
A cursory glance at Iraq's battlefield performance against ISIL gives us a clear insight into what is likely to happen in Mosul over the coming months.
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I say months, because Mosul will not be taken in a matter of weeks, nor will it be taken without the Iraqi Security Forces (ISF), Kurdish Peshmerga and sectarian Shia militias paying a hefty price when the time comes to square away the butcher's bill.
|Peshmerga forces advance in the east of Mosul to attack ISIL fighters in Mosul, Iraq [Reuters]
When Iraq set off to recapture Tikrit last year, we heard on numerous occasions how ISIL will be rolled back, and that former Iraqi leader Saddam Hussein's hometown will soon be back under Baghdad's control.
On March 14, 2015, Karim al-Nuri, a fighter and spokesman for the sectarian Iran-backed Badr Organisation, a significant component of the Shia-dominated Popular Mobilisation Forces (PMF), said that ISIL fighters were surrounded, mere dozens of them remained and that the city would fall "within 72 hours".
As it happened, it took not three days, but a month and a half for Tikrit to be cleared. A force of several hundred ISIL fighters managed to hold off almost 30,000 ISF, PMF and federal police in a battle that could only be described as militarily embarrassing.
Mosul will not be taken in a matter of weeks, nor will it be taken without the Iraqi Security Forces [ISF], Kurdish Peshmerga and sectarian Shia militias paying a hefty price when the time comes to square away the butcher's bill.
As a point of comparison, the Iraqi military in 1988 managed to liberate Iraq's southeastern Faw peninsula from Iranian forces in less than 48 hours.
More recently, it took more than a month for Iraq to regain control of Fallujah, and not without significant cost. Not only were battlefield losses high, but the city was reduced to rubble in a manner not too dissimilar from what happened in Ramadi, the capital of Iraq's western Anbar Governorate.
PMF militias were also exposed as having committed grave atrocities, such as slaughtering Sunni civilians before forcing others to drink the blood of their recently slain fellow prisoners.
If this is what the ISF and its allies can produce operationally on the field of battle, even with extensive Iranian support and US air cover, then how can anyone expect their battlefield performance and capabilities suddenly to improve?
The answer is that we simply cannot, and Iraq's armed forces have certainly not become a better military over the past five months.
Iraqi Prime Minister Haider al-Abadi is bent on prising Mosul from ISIL's grip before the end of the year, perhaps to secure his office against resurgent rivals such as his predecessor, Nouri al-Maliki, who is widely considered to be a virulently sectarian politician.
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However, the clock is ticking and he may not be able to make good on his promise as Mosul is no Tikrit, and it is certainly no Fallujah.
Mosul is Iraq’s second largest city, and ISIL has been in control of it for more than two years. It has therefore had more than ample time to prepare defences, and has done this while staying relatively unmolested.
Most of the heaviest fighting against ISIL was in Anbar, Salahuddin and Diyala, while Kurdish units have maintained a fairly stable line since they snatched Kirkuk and Jalawla from ISIL two years ago.
As such, ISIL will have definitely used this time to prepare for the battle that has now begun. A few weeks ago, reports indicated that ISIL had dug a moat around Mosul and pumped oil into it, ready to create a "river of fire". Live footage from today shows enormous walls of black smoke completely covering Mosul’s frontage in most areas, creating a smokescreen of gigantic proportions.
This stratagem is a larger-scale version of what ISIL did in Qayyarah and Tikrit, where it set oil wells on fire in order to obscure the battlefield and prevent close air support in order to force the ISF to engage it on the ground where it is strongest. Aside from burning vast amounts of oil, ISIL has also sabotaged airfield runways, blockaded roads and undoubtedly littered Mosul with mines and IEDs.
With Iraq's previous battlefield record in mind, as well as the length of time ISIL has had to harden their defences and dig in, we can expect Mosul to be exhaustingly long, bloody and with tragic humanitarian consequences for the 1.5 million civilians still in the city.
Tallha Abdulrazaq is a researcher at the University of Exeter's Strategy and Security Institute and winner of the 2015 Al Jazeera Young Researcher Award.
The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera's editorial policies.
Source: Al Jazeera