TAL RIFAAT, Syria >> Abdul Hakim Yasin, the commander of a Syrian antigovernment fighting group, lurched his pickup truck to a stop inside the captured residential compound he uses as his guerrilla base.

His fighters had been waiting for orders for a predawn attack on an army checkpoint at the entrance to Aleppo, Syria’s largest city. The men had been issued ammunition and had said their prayers. Their truck bomb was almost prepared.

Now the commander had a surprise. Minutes earlier, his father, who had been arrested by the army at the same checkpoint in July, had called to say his jailers had released him. He needed a ride out of Aleppo, fast.

“God is great!” the men shouted. They climbed onto trucks, loaded weapons and accelerated away, barreling through darkness on nearly deserted roads toward a city under siege, to reclaim one of their own.

Yasin was pensive as he drove, worried that the call was a ploy to lure him and his fighters into a trap.

“Often the government does this,” he said. “Usually it is an ambush.”

He had sent an empty freight truck ahead, he said, to check the way. But he never slowed down.

During five days last week, Yasin and his group, the Lions of Tawhid, allowed two journalists from The New York Times to live and travel beside them as they fought their part in the war to unseat President Bashar Assad.

This group falls under the command of Al Tawhid Brigade, a relatively new structure in Aleppo Province that has unified several groups and fights under the banner of the Free Syrian Army, the loose coalition of armed rebels.

While broad extrapolations are difficult to glean from one fighting group in a complex society, the activities and personal stories of these men, a mix of civilians who took up arms and dozens of army defectors who joined them, offers a fine-grained look of the uprising, and the momentum and guerrilla energy it has attained.

Yasin, 37, was a clean-shaven accountant before the war. He lived a quiet life with his wife and two young sons. Now thickly bearded and projecting a stoic calm under fire, he has been hardened by his war in ways he could not have foreseen.

He roams the Aleppo region with dozens of armed men in camouflage, plotting attacks with other commanders, evading airstrikes, meeting with smugglers and bombmakers to gather more weapons, and rotating through front-line duties in a gritty street-by-street urban campaign. He prefers to sleep by day, and fight by night.

His fighters are a cross section of a nation at war with itself. They include a real estate agent, several farmers, construction workers and a nurse who owned a short-order restaurant. These men fight side by side with a cadre of army defectors, who say the government they once served must fall.

The civilians started with stones and firearms bought for hunting. Their first more powerful weapon was a huge slingshot for hurling Molotov cocktails and small homemade bombs. As professional soldiers have joined them, they have gradually acquired assault rifles, machine guns and rocket-propelled and hand grenades. They now control a captured armored vehicle and two tanks.

As they have grown in numbers and strength, they have organized into a force that mixes paramilitary discipline, civilian policing, Islamic law and the harsh demands of necessity with battlefield coldness and outright cunning. They have informants and spies, and eavesdrop on the government’s military radios while trying to form a nascent government themselves in the territory under their control.

But mostly they yearn to fight, seeking to destroy the Assad government and its better-equipped forces by most any means. Their collective confidence that they will prevail both bonds them together and informs their sense that this is their time.

FROM PROTESTS TO ARMS

For the people of Tal Rifaat, a city of roughly 20,000 people on an agricultural plain, the uprising moved in stages from peaceful demonstrations to open war. It began with protests early in 2011, which the government tried to smash.

By midsummer last year, Abdul Hakim Yasin had formed a guerrilla cell with fewer than 10 other residents. They began with four shotguns and hunting rifles against a government with an extensive internal police and intelligence apparatus and a military with hundreds of thousands of troops.

Last September, security forces scattered a protest at the city’s rail yard with gunfire; 83 people were wounded. One man, Ahmed Mohammed Homed, 32, was killed. Yasin said he knew then that they were at war.

“Everyone in Tal Rifaat formed into teams,” he said.

As the gunmen organized ambushes, the city’s machinists and mechanics also went to work, learning to concoct explosives to pack into bombs. The government’s crackdown had spawned an insurgency, in Tal Rifaat as elsewhere.

By this spring, as the army came to occupy Tal Rifaat, the now war-savvy city had all but emptied. The soldiers painted graffiti on the city’s walls. “Assad or nobody,” one scrawl read.

A revolutionary painted a reply: “We will kneel only for God.”

In a fashion as old as guerrilla war, as the ranks swelled, the original members agreed to divide, forming interconnected fighting groups that began to accept army defectors. It was then that Jamal Abu Houran, a Syrian infantry soldier who did not provide his surname, joined with Yasin.

Jamal Abu Houran’s journey from proud Syrian citizen and willing military conscript to antigovernment guerrilla followed the wrenching arc of a young patriot rediscovering his country as it erupted in violence around him.

He had been a student of Arabic literature at Al-Baath University in Homs, where he studied Mahmoud Darwish, the Palestinian poet, and was opposed to Israel’s and the West’s military activities in the Middle East. Two years ago, the army summoned him for compulsory military service. He willingly left behind his books, to be trained in tactics and infantry arms.

As the revolution spread and the government resorted to more violence to blunt it, Jamal Abu Houran’s unease with his own army set in. His military conscription was scheduled to end early this year. Then the army extended his tour without his consent and assigned him to lead an infantry squad — part of an emergency policy intended to maintain manpower to fight the growing insurgency.

It did not work. In early April, Jamal Abu Houran called a friend in Homs, who told him that soldiers had raped an 11-year-old girl. His disaffection became disgust.

“I used to think the army was to defend the country and resist and fight the Western projects in the Middle East,” he said. “My conclusion, after that, was that we were serving in an army that does not protect its own people.”

Using Skype, Jamal Abu Houran contacted an activist from Tal Rifaat who invited him to desert his post and head to a nearby village, where he would be picked up by a waiting car. Soon he was in a hidden guerrilla office. He told the activists there that he had studied weapons well, and asked to join the rebels’ fight.

An activist phoned Yasin, who quickly appeared and stood before him. Jamal recalled his new commander’s first words.

“You are my brother,” he said. “And your blood is more precious than mine.”

Jamal Abu Houran’s reply set his life on its new course.

“I hope God will give me the strength to defend people like you,” he said.

This was his oath.

He had switched sides.

It was mid-April. Yasin, who had recently started his own armed group, had nine fighters, while the army had almost free rein of the Aleppo countryside. One of Jamal Abu Houran’s earliest tasks was to recruit. Persuasion too was a means of waging war: The more soldiers the rebels could lead to desertion, the more they would weaken the army and strengthen their own ranks.

“I started calling people I knew from the army,” he said. “I convinced 12 people to defect.”

As the fighting group grew, Jamal Abu Houran’s role and standing rose. He became one of Yasin’s trusted sergeants — leading small teams in attacks and managing the fighting group’s armory, where he issued and collected weapons with the discipline and a carefully kept ledger that resembled life in the army that had trained him.

SIGHTS ON A CHECKPOINT

By summer, with defections rising and the rebels fighting more effectively, the army’s grip had been loosened. The province’s myriad fighting groups had pushed most of the government’s forces from the countryside. Military units maintained a presence on Minakh air base near Tal Rifaat and at an artillery school near Aleppo.

The main fight had shifted to the city, where many fighting groups, including Yasin’s, had coalesced under the black flag of Al Tawhid, a relatively new brigade that sought to organize and unify the province’s disparate rebel units.

With this new structure came more coordination. Yasin’s group began taking turns on the city’s front lines.

In mid-August the fighters were rotated back to Tal Rifaat, to prepare for an attack, assigned by the province’s revolutionary military council, to destroy an army checkpoint on the northern road out of the city.

Al Tawhid had gathered intelligence for the operation. The checkpoint had two BMPs, Russian-made armored fighting vehicles that supported about 30 soldiers in small buildings. These soldiers were protected by dirt barriers that forced approaching vehicles to slow down and weave.

All of this was watched over by 50 more soldiers in a hospital nearby. Many Palestinians lived in the neighborhood near the checkpoint. The rebels considered these families loyal to the Assad government, which had hosted them for decades. The rebels had been unable to infiltrate the Palestinian turf.

Moreover, the checkpoint was supported by the air force, which could muster helicopters and ground-attack jets. The impending attack would be difficult, and perhaps cost many rebel lives.

Still, the rebels deemed destroying the checkpoint essential. As long as the government controlled it, their routes to and from the city were limited, and the soldiers could screen all the civilians traveling on the road, detaining whomever they pleased.

Yasin knew of this personally. In July, his father, Jamal, had been arrested by the soldiers at that very spot. He suspected it was because the government knew his son led an armed group; He said he expected his father would be killed. This checkpoint, he said, had to be destroyed.

Early last week, Yasin left his fighters in their compound to attend a commanders’ meeting. He ordered them to be ready for the attack when he came back. He returned before midnight and said the attack had been postponed. The fighters were dejected.

The next evening a pickup truck pulled in with a young prisoner. The fighters said the man, whom they called Abu Hilal, was a member of a loyalist shabiha militia, who had been captured and held by rebels in Maara, a small city a few miles away.

Abu Hilal was a lanky man with a shaved head; He flinched and cowered as the fighters crowded around him. He showed signs of extensive beatings. His left arm was swollen with bruises. He limped to the stone steps and sat down, physically and psychologically overwhelmed.

The rebels’ hatred for the shabiha militiamen borders on electric. One fighter, Antar, stepped between Abu Hilal and the jeering fighters, to protect him. He led the prisoner inside to the kitchen, where Deeb Meldaoun, the trained nurse who serves as the fighters’ cook and medic, had him undress so he could examine his wounds.

Purple bruises covered Abu Hilal’s back and left leg.

Yasin stood in the doorway and invited the prisoner to relax.

“Do you want to take a shower?” he said.

“No, thank you,” Abul Hilal said softly.

“You will sleep well if you do,” Yasin said.

The fighters provided Abu Hilal with bread and jam, then cigarettes, and said they would find him an identification card, so that he could travel once they set him free. Gradually they lost interest in him. He crouched alone on the kitchen floor, smoking.

In his office next door, Yasin seemed thoughtful. He smoked cigarette after cigarette. Abu Hilal had been an inmate in a government prison before the revolution, he said, and was let out of jail to provide muscle to the shabiha militias. He had confessed in the revolutionaries’ provisional court to committing a rape and six murders recently, the rebels said. The court had sentenced him to death.

Yasin said he had opposed executing the man. He had asked the revolutionaries, he said, to release Abu Hilal into his custody so that he might arrange a trade, perhaps a prisoner exchange or a ransom to be paid in weapons.

“He is a bad man,” he said. “But let’s use him to benefit the revolution.”

AN UNEXPECTED AMNESTY

That night Abdul Hakim Yasin left for another meeting about the checkpoint attack. Jamal Abu Houran issued weapons and ammunition. The fighters prayed.

Yasin returned in a rush, honking his truck’s horn. He shouted that his father had called and said he had been unexpectedly let out from prison. They needed to rush to retrieve him. The men cheered, climbed onto their trucks and sped south toward Aleppo.

In the lead truck, Yasin repeatedly tried to call a friend he had sent ahead in civilian clothes in an empty freight truck. He was expecting a trick, and wanted the lead driver to ensure that his father actually was free and there was no trap. Then the fighters could drive in.

At the outskirts of the city, he reached the other man, who reported that he was with Jamal Yasin, driving north.

For a moment, Yasin seemed less the guerrilla commander than a son. He ended the call. He drove in silence, letting the news sink in. Then he spoke.

“God is great,” he said.

In the darkness of the abandoned road, the other truck approached and stopped. Jamal Yasin climbed out. He was a straight-backed and squarely built man with a shaved head. He looked unhurt.

The fighters hurried him to the front seat of the first pickup truck, where he sat beside his son for the drive to Tal Rifaat.

Jamal Yasin said he had not been tortured. But the prison cell was tiny and so overcrowded that he almost could not sleep.

Abdul Hakim Yasin admitted to his worry.

“I was 99 percent sure it was an ambush,” he said.

His father listened, then gently admonished his son.

“You really think if it was an ambush I would call you?” he said. “Even if they were slitting my throat?”

“Daddy, I swear to God I am under big pressure,” Abdul Hakim said.

“Take it easy, my son, there is no stress,” the father answered.

A LONG-PLANNED ATTACK

Abdul Hakim Yasin dropped off his father at his brother’s home in Tal Rifaat. The fighters stood outside, exhilarated at the reunion, shouting thanks to God. Yasin drew his pistol and emptied it into the night sky. He was grinning.

“Let’s go,” he said.

There was still a checkpoint to attack. First Yasin wanted to celebrate. Back at the base, he gave his fighters ice cream. The gunmen savored their treat, praising the good fortune that had surprised them all.

“I thought I might never see my father again,” Yasin told them.

He excused himself and returned to his office to meet a fellow commander to discuss the last details of the impending attack. The two men huddled over a hand-drawn map.

The attack would begin shortly, Yasin said, timed to begin about an hour before dawn, when he expected most of the government soldiers to be asleep. The fighters returned to prayers, or snatching bits of rest.

Abu Hilal, the prisoner, huddled against the wall, watching.

Just before leaving, he was led outside blindfolded and put into the back seat of one of the pickup trucks.

“Tonight we will do the exchange,”Yasin said.

He quickly walked through a large hole cut in the compound’s back wall and approached a flatbed truck. The bed held a stack of thick pipes packed with homemade explosives. Electrical wires protruded from their back ends, all of them joined in a trunk line. This was a truck bomb, wired to detonate remotely.

“Three hundred kilograms,” Yasin said.

He revealed more of his plan. The rebels lacked the heavy weapons to take the checkpoint in a head-on fight. So several of them would dress as civilians, move the truck bomb near the checkpoint and set it off. This would be the signal for an assault over the ground.

There was one problem. The Lions of Tawhid said they did not believe in using their fighters as suicide bombers.

Two fighters poured fuel into the truck’s gas tank while Meldaoun, the nurse, snipped branches from shrubs and stacked them on the bomb, hiding it from view.

The real plan was beginning to emerge. It involved the prisoner, Abu Hilal. The assurances that he would be released had been a deception. The fighters intended to put him behind the wheel of the truck bomb near the checkpoint and tell him to drive forward in a prisoner exchange.

Adel Meldaoun, a cement worker who serves as one of Yasin’s deputies and is the nurse’s brother, started the flatbed truck and swung it off the dirt path onto the main road; the pickup trucks had already driven away, packed with gunmen.

“Halab,” Meldaoun said, using Aleppo’s ancient Arabic name.

He stepped on the gas to catch up with his commander. The convoy was gone, with Abu Hilal in one of the seats, blindfolded, rushing toward an almost certain death.

THE GAME OF FATE

Shortly after sunrise, the fighters returned. They trickled back in, clean and unbloodied. They did not look as if they had fought. A few shook their heads, grimaced and made their way inside to return their weapons to Jamal Abu Houran.

Their commander pulled up and stepped out of the truck. His face was long, his eyes tired. The waiting fighters did not approach him. At last he explained.

“We failed,” he said.

They had arrived near the checkpoint, he said. All appeared perfect for the attack. Most of the soldiers were asleep. A few sat outside at a table, playing cards. His fighters took their positions and the final act ran its course.

“We told Abu Hilal, ‘Go, drive that way, your father is waiting for you there, don’t do any bad things in the future,”’ Hakim said. “And he was so happy, and he drove.”

Abu Hilal stopped the truck at the checkpoint. Abdul Hakim Yasin pushed the button on the remote detonator, ready for the flash and thunderclap of more than 650 pounds of explosives. It would be the signal for his fighters to move forward and mop up.

Nothing happened.

He pushed the button again.

The truck did not explode.

Yasin suspected that the checkpoint was equipped with a jammer that blocked the signal.

Now he sat in his office, disappointed at the failure, amazed that his own family remained intact. He was exhausted. Everyone he had expected to die — his father, his prisoner, the soldiers at the checkpoint — was alive.

“It is,” he said, “the game of fate.”

THE URBAN STANDOFF

A few hours later, back in camouflage, Abdul Hakim Yasin led his fighters to Aleppo. Their assignment at the checkpoint had ended; they were due back at the front lines.

The commander steered wide of the checkpoint. He chose another, longer route, driving with the trucks spread out and at headlong speeds, to limit exposure to attack helicopters and jets.

Once within the city, the trucks weaved through neighborhoods until reaching a cluster of buildings under rebel control. They hid the vehicles in the shade of trees and walked briskly inside, moving into an apartment abandoned by a fleeing police captain. It was a place to stay until dark.

There they watched the government’s televised news; The presenter told of a bomb attack in Damascus, the capital. Reclining on the police captain’s couch, barefoot and drowsy after a night without sleep, Yasin was amused. His humor had returned. He chuckled.

“Maybe Abu Hilal drove all the way to Damascus,” he said.

His fighters were rummaging through the apartment. One found the remote control for the air conditioner, and turned it on. Others rummaged through the family’s collection of bootleg DVDs. More packed up books to take home. Another cooked a meal on the captain’s stove, and served his commander tea in the captain’s cups.

A fighter came to Yasin. He had found the captain’s wedding album. Yasin flipped through it slowly, page by page, stopping when he saw women in the bridal party wearing clothes that clashed with his traditional rural tastes.

“That dress is too short for me,” he said.

Soon he was asleep on his enemy’s couch, resting for his next mission from Al Tawhid.

Outside, as the fighters dozed, waiting to move to the front lines that night, a government helicopter and light-attack jet strafed and fired rockets into the city. Mortar and tank shells exploded intermittently. The men paid it all little mind.

Then the cycle started anew. Yasin woke before sunset. He was not fasting during Ramadan, so he ate quickly and left for a meeting with other commanders. He returned by darkness with orders and organized his fighters into teams. His fighters in turn distributed ammunition and formed a convoy that soon snaked through Aleppo, toward a city block ablaze.

There, they said, another rebel unit had ambushed a government convoy, disabling vehicles and trapping many soldiers. Yasin’s fighters were to relieve the other rebels and cut off one possible avenue of the soldiers’ escape.

As they approached, gunfire ripped by. The convoy turned into an industrial compound, and the fighters hopped off the trucks, parking them against the warehouses, and fanned out.

Yasin watched, silhouetted by the orange blaze. His enemies, trapped nearby, lobbed mortar rounds at the compound. Each exploded with crunching blasts. He did not flinch.

Another jet showed up and circled overhead. It was invisible in the almost moonless night sky; only its engine could be heard. Soon it attacked, too, diving toward the compound and firing air-to-ground rockets in pairs.

It pulled out, circled, returned, dived and released rockets again. They slammed to earth at the compound’s edge.

In the climate of many conflicts, this might be read as a dispiriting, lopsided encounter. The rebels could not see the aircraft. Even if they could, they had nothing with which to fire back effectively. The pilot attacked them at will, aided by the orange flow of the inferno across the street, which illuminated the contours of the compound where the fighters were hiding.

But as the rockets struck, the Tawhid fighters were barely distracted. They were waiting for the government soldiers nearby to show themselves, certain that night by night their foes were growing weaker, and their uprising was gaining strength.

After each explosion, Yasin, an accountant leading a life and a role delivered to him by war, keyed his two-way radio, and checked on his men. All around him they crouched in the smoky darkness, weapons ready, waiting for orders or for more action against a government they consider already dead.

© 2012 The New York Times Company