ANGI, Afghanistan, Nov. 13 — The scene was set for Northern Alliance troops to make another triumphant entrance into a city liberated from the Taliban. And then everything went wrong.

Early this afternoon, the word spread that a Taliban commander in Kunduz, in northeastern Afghanistan, had switched his allegiance to the Northern Alliance and invited its troops to enter.

"Kunduz has been captured!" the Northern Alliance soldiers roared, and the tanks and troop carriers started their engines and rumbled toward the city.

But when the Northern Alliance troops approached the fringes of Kunduz, they were met not with cheering crowds but with Taliban rockets. The soldiers, stunned, began to panic. So did the Northern Alliance commander, Daoud Khan, who stood on top of a hill, jerking his head about in confusion.

"I don't know what is happening," the commander said, his face drained of color. "We made contacts with commanders in the city. They told us they would embrace us."

With that, Commander Daoud, one of the senior military leaders of the Northern Alliance, scampered down the hill, jumped into his car and sped away from the front lines. Taking his cue, hundreds of soldiers followed, falling down, falling under car wheels, yelling and shouting, trampling one another in a panic to get away.

"Let me on, let me on!" soldiers yelled, leaping onto car hoods and troop carriers as they ran from what appeared to be a Taliban ambush and counteroffensive. Some men were run over in the pandemonium. The drivers of troops carriers, desperate to get away, left their men behind. The retreat stretched more than a mile and was halted only when a Northern Alliance soldier threatened to shoot anyone who went any further.

The Taliban assault never came. But their defiant defense of Kunduz, even as their comrades across Afghanistan have been left reeling, suggests that the battle-hardened army, even if mortally wounded, has some life in it yet.

The confused series of events that led to today's panicked retreat revealed, if for only a moment, the fluid allegiances and conflicting loyalties that very likely will form the backdrop of any Afghan government that succeeds the Taliban.

If, as Northern Alliance leaders say, they will refuse to work with any former members of the Taliban in a new Afghan government, they might have to exclude many soldiers in their own ranks. The rapid-fire collapse of the Taliban in the past week was made possible in large part by the defections of dozens of Taliban commanders and thousands of their troops.

At the outskirts of Kunduz today, the familiar script went astray.

"In Afghanistan, this is the way wars are fought," General Rosmuhammad Uria said with a shrug as he spoke of the back-channel negotiations with Taliban commanders. "If the Taliban commanders agree to embrace us, all will be forgiven."

By the late afternoon here, the Northern Alliance had gathered itself again, and its soldiers were marching back toward Kunduz. Fresh troops came as well, more than 2,000 of them, most of them confidant that the Taliban's final days are ticking away.

Yet in Kunduz, the Taliban's demise doesn't seem so sure. The Taliban garrison there, plus the remnants of the forces that retreated from Mazar-i-Sharif and Taliqan, are trapped. All their escape routes, including the road to Kabul, have been cut. Northern Alliance leaders say Taliban forces there number 20,000, but that estimate is impossible to verify.

That leaves Taliban soldiers there with two choices: fight or defect.

As the day dawned, Northern Alliance commanders were playing the same game of chicken that has determined the outcomes of battles across the country. As they readied their men for battle, the commanders pleaded with Taliban commanders to switch sides. Hours before the attack on Kunduz was set to begin, Commander Uria said he had obtained secret agreements with a number of Taliban commanders in Kunduz to allow the Northern Alliance to enter the city.

"Maybe there will be no fighting," he said.

It was the same sort of combination of threats and cajoling that helped to secure the Northern Alliance's capture of nearby Taliqan earlier this week. The city fell to the Northern Alliance not because the Taliban was defeated in battle, but because several Taliban warlords agreed to switch sides. They brought with them 5,000 soldiers, who quickly blended into the ranks of the Northern Alliance.

The erstwhile Taliban commanders balked at any suggestion that they had ever had divided loyalties.

"I was with the Taliban, yes, but all along I was spying on them," said Adbullah Gard, one of the Taliban commanders who defected and brought 1,000 troops over to the Northern Alliance.

The ease with which the Taliban and Northern Alliance accept one into the other's ranks may help explain why, at least so far, there have been relatively few reports of atrocities against the Taliban as the movement collapses.

"If the Taliban troops embrace us, we will forgive them," Abdul Haq, a young Northern Alliance soldier, said before the battle.

In Bangi, it looked as if the game of chicken was going to work. Up until the last moment, Commanders Daoud and Uria said they were confident they would be entering Kunduz without shooting, and that the Taliban soldiers would come over to their side. Then the shooting started, and chaos ensued.

Later, Commander Uria said he would try again to capture Kunduz with as little shooting as possible. Whether the Taliban troops stranded in Kunduz will oblige them remains unclear, but there were hopeful signs.

As the setting sun cast a pink glow on the mountains here, a strange figure appeared on the horizon. He looked gaunt and bedraggled, and he walked toward the Northern Alliance lines. He was a Taliban commander, Abdullah Mutalib, and he had decided to switch sides.

"I am tired of fighting with the Taliban," Mr. Mutalib said, as the Northern Alliance soldiers gathered round to embrace him.