QUSAYR, Syria -- As representatives of the more than 70 countries dubbed Friends of Syria met in Paris on Thursday to discuss aid to the country’s opposition, some of the fighters here wondered if it might already be too late.

"Maybe this will be the end," said Ammar al Bukiyah, one of the leaders of the Farouq Brigade, the largest group of rebels operating under the umbrella of the Free Syrian Army, the loosely organized armed opposition to Syrian President Bashar Assad. As Bukiyah spoke, shells and rockets fell nearby, rattling the windows of the house that had become a makeshift military base.

Many of the fighters in this largely empty city that was once home to about 35,000 people came here from nearby Homs, Syria’s third largest city, at the end of February, when they abandoned their positions in the Baba Amr neighborhood after weeks of fierce shelling. Since then, the fighters here controlled Qusayr’s northern half, a position that has appeared tenuous more than once as the Syrian military expanded its offensive against the rebels all over the country. On Thursday, the rebels fought the army for the second day in a row as pro-Assad tanks and troops attempted to enter rebel-held territory from the east.

At the beginning of March, the rebels here had said they would leave Qusayr so as not to condemn it to the same fate as Baba Amr, which was largely destroyed by shelling before loyalist ground troops moved in. But as the rebels have run out of places to go, that seems to have changed. "We will fight to the death," said Bukiyah, a 35-year-old house painter wearing a black tracksuit who spoke as he helped manage a battle that began around 8 a.m. and ended in the early afternoon.

The rebels claimed to have destroyed a pair of Syrian tanks and an armored personnel carrier, as well as killing more than a dozen Syrian soldiers in the two days of fighting. The driver of a Syrian tank also defected during the battle, according to the rebels.

The battle here shows the complexity of the conflict that now simmers in Syria. While the anti-Assad movement began as peaceful demonstrations against a repressive government, it has for much of the past year become a struggle between armed rebels and the better-equipped Syrian military. Neither side is willing to concede turf to the other in the wake of a U.N.-brokered cease-fire that went into effect a week ago.

In Paris, U.N. Secretary-General Ban Ki-moon demanded that Syria pull its forces out of cities and town, saying keeping troops and tanks in populated areas violated the terms of the cease-fire. But he stopped short of saying the cease-fire had failed and called for the Security Council to approve the dispatch of as many as 300 monitors to determine whether the two sides were adhering to the cease-fire.

There are few civilians left in Qusayr and surrounding towns and villages. Those who have remained seem to have grown accustomed to the sounds of gunfire, shelling and rockets, walking calmly through a neighborhood that was home for dozens of fighters.

As evening fell, the rebels were preparing for a third day of battle. Bukiyah used Skype to talk to Abdel Rizaq Tlass, the leader of the Farouq Brigade, asking him for reinforcements and weapons. Tlass remains in Homs, which looks increasingly as though it will be abandoned by the Free Syrian Army after two and a half months of heavy shelling.