Aleppo, Syria’s pre-war industrial and economic hub, has emerged as the civil war, high-stake battlefield, as warring parties pour in all of their military might in an effort to strike a definitive blow against their opponents. In the first year of the revolution Aleppo saw neither large-scale protests nor the deadly violence that shook other towns and cities. However, it suddenly became a key battleground in July 2012, when rebel fighters launched an offensive to oust government forces and gain control over northern Syria. Aleppo has been divided since then between the government and the rebels, with the Assad government holding the west while rebels controlling districts in the east and much of the surrounding countryside of Aleppo governate, even some parts of the city changing hands on a daily basis now. According to the International Committee of the Red Cross the battle of Aleppo is one of the most devastating urban conflicts in modern times. There has been massive damage to the city’s basic infrastructure. With water and electricity supplies cut or severely reduced, the population is at risk from untreated and unsafe water. Humanitarian organisations have begun trucking drinking water as an emergency measure. Recently, Assad’s regime tightened the siege around Aleppo to force the rebel fighters to surrender but rebels hit back by breaking the siege. But one vital question arises: why has Aleppo become so crucial for both the Syrian regime and the opposition? As Aleppo used to be the largest city in Syria its recapturing for the President Bashar al-Assad regime would be of military and psychological significance, and liberating this particular city would be a boost to the Syrian government’s popular legitimacy. On the other hand, Aleppo is the last major urban holding of the mainstream, armed opposition in Syria. If the political process is to amount to anything other than a regime victory in all but name, the rebels have to hold Aleppo bity. Both sides are throwing everything they can at the four-year battle for the city, a fight that has come to define the Syrian civil war, because both sides believe the fate of Aleppo would decide the outcome of the conflict. The Syrian government has organised a good number of forces thorough the participation of its own regular Syrian Arab army, Hezbollah and Shia militias; it should not be forgotten that these forces are also supported by Russian airpower. On the other hand, rebels have also mobilised a number of groups including the Free Syrian Army, Jaysh al-Fateh, Jabhat Fateh al-Sham (formerly Jabhat al-Nusra) and Ahrar al-Sham. Like the opposition, President Assad and his inner circle are convinced that taking Aleppo would effectively end the civil war, breaking the morale of the opposition and condemning it to a marginal existence as a rural insurgency that can no longer claim to represent the large sections of Syrian society. Bringing all the country’s major cities under his control will also remove the threat that Assad’s international critics could push, as they once did, for a new Syrian settlement that does not include him as the leader. Moderate members of Syria’s opposition argue that they fear not just for the people of Aleppo, but for the state of their wider cause — the Syrian revolution — and believe the siege is aimed not just to force the rebels fighters to surrender but also to polarise further a war that Assad has always cast as a battle between himself and extremists. The fact is that in Aleppo a race of reinforcements is going on between the government and the opposition. It is difficult to assume how long the battle in Aleppo would last, as that would depend on the speed of transfer of reinforcements. In the next few months it would be a test for the government forces and opposition fighters. If the government is able to take full control of Aleppo, it would have control of all major urban centres of the country including Hama, Homs and Damascus, which is the spine of the country. And that is what concerns the regime and its sponsor in particular. It would then allow them to free up forces, potentially, to go on the offensive elsewhere, most likely directly into the Idlib province, and eventually into the south. After that they could turn their attention finally to ISIS’ de facto capital Raqqa. But all of these things would take time, probably months or years to fully institute. It is a high possibility that the Syrian regime and its allies are going for a whole-country solution to the Syria crisis based on the Assad regime control of the key cities, and Aleppo would be the major step in this direction. The defeat of the Aleppo insurgents could have been seen in Damascus as a precursor to the collapse of the armed rebellion against Assad’s rule. The writer is a columnist for the Middle East and Afghanistan-Pakistan region, and Editor of ViewAround, a geopolitical news agency. He can be reached at manishraiva@gmail.com