Month after month, the ancient city of Aleppo in Syria’s northwest was a haven in its own world, isolated from the violence, massacres and bomb attacks that were pulverizing dozens of other cities across the country.

Aleppo, known as Syria’s commercial and economic center of power, operated as if everything was normal: stores were open, gasoline was available for purchase and families were free to walk from place to place without the threat of being arrested, beaten or killed. Yet with the regime of Bashar al-Assad slowly but surely starting to lose control over what was once considered a government stronghold, it is as if the calm that was once so reassuring in this city was just a long and pleasant dream.

Indeed, the same metropolis that was labeled by activists and outsiders alike as too calm to join the revolt is now thrust right in the middle of it. Battalions of men from the rebel Free Syrian Army have taken at least a third of the city’s neighborhoods, setting up checkpoints and trying to keep the loyalist army out of others.

Over the course of the uprising, the FSA has managed to carve up a series of “free” zones in Syria’s northwestern Idlib Province which remain largely outside of the Syrian government’s reach. It was only a matter of time before the young men of the FSA attempted to expand that zone into Syria’s most populous city.

Tired and worn out, the Syrian army is stretched thin throughout the country to the point of having to call in reinforcements from the Golan Heights last week to defend the capital from an FSA assault. Only after a quick and impromptu deployment of heavy weapons, combat helicopters and mortar shells did Assad’s men push the rebels back into the outlying districts, miles from inner Damascus. However demoralizing that operation was to those seeking Assad’s ouster, it has done nothing to dampen their determination in Aleppo, where bold moves into the city’s southwest and northeast corners have forced the regime to call once again on their troops for urban combat.

Of course, to expect Bashar al-Assad and his security advisors to willingly hand over Aleppo would be a fool’s paradise. Assad understands just as much as his adversaries how strategic and symbolic Aleppo is. Unlike the battle for Damascus, which needed to be fought quickly and with some degree of improvisation, the Syrian army is taking its time to formulate a game plan for Aleppo before counterattacking.

Parts of the city may currently be in rebel hands but the reality for the Free Syrian Army is much bleaker than it would appear.

Aleppo is virtually surrounded from all sides by a Syrian army waiting for their marching orders. Dozens of tanks have been assembled on the outskirts of town just for this operation. FSA commanders in Idlib Province have reported that a significant number of Syrian troops have been recalled from their bases and redeployed to Aleppo, with the most damaging weapons in hand.

If there was any question whether Bashar al-Assad was intent on sticking around to the end, it was this week, when the BBC reported that fixed-wing aircraft were deployed against opposition areas for the first time. Artillery rounds, jet fighters and helicopter fire have been used by the army for the past week, hoping that such an incessant amount of firepower will loosen FSA defenses before a full-scale invasion of the city.

Tens of thousands of civilians have fled Aleppo to surrounding areas, knowing full well that the homes they have lived in for generations may not be standing if and when they come back.  The Syrian government is speaking in existential terms, calling the Aleppo operation “the mother of all battles.”

Syria’s rebels are dug into their positions, waiting bravely for a fight. But it will take far more than high spirits and courage to withstand an attack from a government that has shown its lack of humanity for the past year and a half. The Syrian resistance may be full of morale and purpose but Assad is armed with the most lethal and indiscriminate weapons available. If precedent is any guide, all of those weapons are likely to fall onto rebel targets, with no mercy for human life and no consideration for the integrity of a city with such cultural heritage.

Honor and sacrifice aside, the FSA will be routed from Aleppo by the Syrian army’s far more effective weaponry. But the opposition movement will regroup as it has in the past and live to fight another day.