Warfare in Syria's biggest city rages

(CBS News) A major battle is shaping up for Syria's largest city. Aleppo is about the size of Los Angeles, and part of it is held by rebels trying to overthrow the 42-year-old dictatorship of Bashar al-Assad.

Assad is trying to crush the rebellion which began nearly a year and a half ago.

syria, opposition, rebels, free syrian army, aleppo
A fighter from the Syrian opposition aims fire during clashes with forces loyal to President Bashar al-Assad, in the center of Syria's restive northern city of Aleppo on July 25, 2012. The Syrian army and rebels on July 25, sent reinforcements to Aleppo to join the intensifying battle for the country's second city, as UN chief Ban Ki-moon urged the world "to stop the slaughter."

CBS News correspondent Elizabeth Palmer reports Syrian helicopters flew over Aleppo Wednesday, but according to activists, they were not shooting, just spotting the positions of rebel fighters on the ground for the next assault.

A Free Syrian Army commander made a bold claim: "We have captured half the city."

But how long can they hold on in these neighborhoods? They're equipped for street-by-street fighting, guerrilla-style, though no match for air power or the regime's heavy artillery, which is already on its way.

The fight for Aleppo will be fierce. It's a strategic prize. If the rebels take it -- on top of town of Azaz, which they won earlier this week -- the area would form the first Free Syrian Army-controlled zone, all the way to the Turkish border.

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The United Nations and the international community are still calling for dialogue in Syria, but dialogue has been drowned out by the din of war.

Civilian casualties -- like victims of shelling -- are just hoping to survive, and the armed men on both sides are determined to win, not talk.

Members of the Free Syrian Army are concerned this is going to be a long fight, and a very costly one.

Some tell CBS News they also are concerned about what they see as a split in the Free Syrian Army. They say that the fundamentalist Islamic brigades are getting more money, more support, and maybe even the upper hand in this fight, and that's not going down well with everybody.

CBS News correspondent Clarissa Ward -- one of the few Western correspondent inside Syria - reports that in at least one village where Syrian tanks withdrew recently, residents say they're thrilled to have their liberty. However the scene they left behind was devastating.

People told CBS News that helicopter gunships swooped in Thursday and obliterated an entire street. Rockets left giant craters. It will take the residents of this village years to rebuild the damage that their own army has done.

Even their newfound liberty is not guaranteed. Those tanks only went to join the battle that is raging just north in Aleppo, and if regime forces manage to crush that rebellion you can be sure they will be back soon.