If this battle for Mosul ends in defeat for Isis, we shouldn’t feel too optimistic about what comes next

At one time the caliphate ruled territory with a population of five or six million people, where it sought to establish a truly Islamic State. It is this dream – or nightmare – that is now being shattered. But the groups who fought Isis may soon be fighting each other

Will the fall of Mosul mean the end of the caliphate declared by Abu Bakr al-Baghdadi? (Getty)

After Isis captured Mosul in June 2014, people in Baghdad waited in terror to see if its fighters would go on to storm the capital. There was very little to stop them as the Iraqi army in northern Iraq broke up and fled south. Many government ministers and MPs rushed to the airport and took refuge in Jordan. When an American military delegation arrived to review the defences of Baghdad, they were told by a senior Iraq official “to look to see which ministers had put fresh sandbags around their ministries. Those that have done so like myself will stay and fight; where you see old sandbags it means the minister doesn’t care because he is intending to run.”

Two and a half years later, it is Isis fighters who are battling street-to-street to hold onto west Mosul, their last big stronghold in Iraq, in the face of multiple assaults by a revived Iraqi army backed by US airpower. The last road out of the city to the west was cut by Iraqi government forces on 1 March and they have also captured one of the half-ruined bridges over the Tigris River that bisects Mosul, which they are planning to repair using US-supplied pontoons. Iraqi military units backed by some 50 US airstrikes a day are getting close to the complex of buildings that used to house the government headquarters in the centre of the city.

Iraqi officials and officers announce only advances and victories, reports that often turn out to be premature or untrue. But there is no doubt that the Iraqi security services are winning the struggle for Mosul, though fighting could go on for a long time amid the close-packed buildings and narrow, twisting alleyways. Already shelling and airstrikes are causing heavy casualties among families sheltering in cellars or beneath the stairs in their houses.

The battle will probably continue for a long time, but the capture of Mosul looks inevitable and will be a calamitous defeat for Isis. When its few thousand fighters seized the city and defeated a government garrison of 60,000 in 2014, it portrayed its victory as a sign that God was on its side. But the same logic works in reverse and today all Isis can offer its followers is a series of hard-fought defeats and withdrawals.

The crucial question concerns whether or not the fall of Mosul means the effective end of the caliphate declared by its leader Abu Bakr al-Baghdadi. The caliphate’s significance was that at one time it ruled territory with a population of five or six million people in Iraq and Syria, where it sought to establish a truly Islamic State. It is this dream – or nightmare – that is now being shattered. Isis may still control some territory in Iraq and more in Syria, but it has nothing like the human and material resources it enjoyed at the height of its power when it controlled territory stretching from the Iranian border almost to the Mediterranean coast.

Isis still has some strengths, including experienced and skilful commanders leading a core of fanatical fighters numbering as many as 4,000 in west Mosul alone. They have already killed 500 and wounded 3,000 of the Iraqi security service’s best soldiers in the struggle for east Mosul, which was meant to last a few weeks and instead took three months. There is a no reason the same thing should not happen in the west of the city where the warren of streets gives the defence an advantage. Foreign fighters know they cannot blend into the population and escape, so they have no choice but to fight to the death.

Other factors work in favour of Isis: it is fighting a vast array of enemies forced into an unwilling coalition against Isis because they fear and hate it just a little bit more than they hate and fear each other. As Isis weakens and becomes less of a threat, the edgy détente between different anti-Isis forces, such as the Iraqi government and the Iraqi Kurds, will begin to fray. People in Baghdad recall that the Kurds took advantage of the defeat of the Iraqi army in 2014 to grab extensive lands long disputed between themselves and the Arabs. Once freed of the menace of Isis, non-Kurdish Iraqis will want these territories back.

In Syria, there is an even more complicated three-cornered fight between the Syrian President Bashar al-Assad, the Syrian Kurds and Turkey for the areas from which Isis is retreating. Turkish troops and their local proxies have just taken al-Bab, northeast of Aleppo, from Isis after a hard fought siege, and have started attacking the town of Manbij nearby, which was taken from Isis after a long battle late last year by the Syrian Kurdish People’s Mobilisation Units (YPG) and its Arab allies. As Isis is driven out, the YPG and Turkish-backed forces are left facing each other in what might be the beginning of a new Kurdish-Turkish war waged across northern Syria.

Even those familiar with the complexities and shifting alliances of the Syrian civil war are baffled by the likely outcome as the different players in Syria position themselves to take advantage of a likely attack on Raqqa, the de facto Syrian capital of Isis. Will the US continue to use the devastating firepower of its air force to support a YPG-led ground offensive? Or could the US administration under Trump take a more pro-Turkish stance and, if it did so, would the Syrian Kurds look for an alternative military alliance with Assad and his Russian backers?

The answers to such questions will decide if we are really getting towards the end of the terrible wars in Iraq and Syria that have ravaged the region since 2003 or if we are only seeing an end to a phase in the conflict. In Iraq, the government has survived the disasters of 2014 and is about to defeat Isis in Mosul, though the Baghdad administration remains spectacularly corrupt, sectarian and dysfunctional. Assad in Syria has already won a crucial victory by capturing east Aleppo, the last big urban stronghold of the armed opposition in Syria, and is evidently intending to win back the whole country.

These successes give an exaggerated idea of the real power of the Iraqi army, which owes the reversal in the military tide to the support of foreign powers and, above all, to US airpower. The same is true of the Syrian army in its reliance on Russia and Russian airstrikes. So far, the mix of cooperation and rivalry between the US and Russia in Syria that developed under President Obama has not changed much under Donald Trump.

Yet the war is not quite over. Isis has a tradition of responding to defeats on the battlefield by carrying out terrorist attacks in the region, Europe, Turkey or other parts of the world. Some spectacular atrocities would enable it once again to dominate the news agenda and show it is not beaten.

Isis may want to test the Trump administration and see if it can provoke it into an overreaction by some act of terror, just as al-Qaeda was able to do at the time of 9/11.