With residents leaving in droves, the battle is seen as a turning point.
BEIRUT, LEBANON - Thousands of frightened refugees poured out of the embattled Syrian metropolis of Aleppo on Tuesday as the military's fighter jets stepped up bombing raids and rebels said they were struggling to hold some of the city's neighborhoods while mounting new assaults in others.
It was an especially violent day all over the country, with activists reporting shelling and clashes in at least a dozen areas, adding hundreds of new bodies to a death toll that has already surpassed 21,000, according to the Syrian Observatory for Human Rights, an anti-government activist group based in Britain. But Aleppo, Syria's largest city, with an ancient and foreboding citadel at its center, seemed on course to become the country's Gettysburg.
"The regime is ready to destroy all of Aleppo," said Talal Atrissi, a Lebanese political analyst. "The regime will never allow the fall of Aleppo because it would start a countdown to their demise."
Syrian troops and rebels have been sending in reinforcements since the battle for the city started nearly three weeks ago. Gunfire is a constant. Residents say every day brings new stories of death, desperation and casualties suffered over small gains -- a police station, a corner, a bakery.
Nearly everywhere, the sounds of traffic have been replaced by the thunder of helicopters and jets.
"Those MiGs," said Mohammed, an activist in Salaheddiin, the city's most contested area, referring to the Russian fighter jet, "they have become our daily bread."
Fighting seems to be spreading. The rebels say they have set up a front in the east. The army draws strength from a military air base in the south, and most of the battles for the city have occurred in between. On Tuesday, the rebels said they had attacked a new neighborhood in the north. A Kurdish area where the government had called on Kurdish militias for help quickly became the subject of disputed narratives.
Hachem al-Haji, one activist in Aleppo, said the rebels moved into the area because local Kurds, after initially supporting the government along with other minorities, are growing more supportive of the opposition. Another activist said that the rebels met fierce resistance from residents fighting as part of the Kurdish militias.
The fight nonetheless began to fade with a punishing blow -- activists and rebels said jets dropped bombs, forcing rebels to flee. There also have been bombs dropped near Aleppo's downtown, the old city famous for its architecture and markets since the ancient Silk Road passed through its center, causing some Syrians to worry that President Bashar Assad is destroying not just his country's present but its past.
The city, by all accounts, has been transformed already. Photos from inside show rubble and shattered glass all over the city, and yet residents who have stayed, unlike the thousands who are increasingly fleeing to Turkey, now say they are preparing for the worst.
Secretary of State Hillary Rodham Clinton, a vocal opponent of Assad, said the Aleppo fighting, combined with defections of former Assad loyalists, all pointed to the eventual demise of his government.
"I'm not going to put a timeline on it," she told reporters in South Africa, where she was on a state visit. "I can't possibly predict it, but I know it's going to happen."