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The day before, the militants captured the vital trading hub Mazar-i-Sharif. It is north-west of the capital Kabul, to which local commander Atta Mohammad Noor and other militia leaders loyal to the government had fled.
Within 24 hours, Afghanistan’s president declared defeat by the Taliban. Before the day’s end, the militants had surrounded the capital and its presidential palace.
Kabul was now isolated and fears loomed over an imminent attack on the capital. The UN warned of catastrophic urban warfare in the city of 4.5 million people, which was swelling with internally displaced people while richer citizens sought to leave the country.
The US embassy began flying its diplomatic staff and personnel to safety by helicopter. It ferried staff from the building’s roof to Kabul airport, a scene reminiscent of the fall of Saigon in 1975, when the US embassy of South Vietnam was similarly abandoned.
Canada, Britain, Germany and others joined the evacuation effort. Government employees went home early, and banks and private businesses closed.
To the relief of some, the Taliban released a statement saying they would not take over the city by force and would await a “peaceful transition” of power.
The details of what that changeover entailed were uncertain but unconfirmed reports began to circulate that President Ashraf Ghani was preparing to relinquish his power to the group.
The Taliban and the Afghan government’s acting interior minister issued separate statements reassuring citizens that Kabul would remain unharmed. But the Taliban later announced the formation of the Islamic Emirate of Afghanistan, a nod to their harsh regime of the same name that ruled most of the country from 1996 to 2001.
By Sunday evening it was clear that no large urban battle for Kabul was under way. This would be of little comfort to thousands of Afghans struggling to board flights out of the country.
The post-civil war Afghanistan, a 20-year effort to instill democracy led by an internationally recognised government, was no more.
Within hours of the Afghan army’s capitulation, Mr Ghani left Afghanistan, as did a few of his close compatriots.
Afghanistan's Tolo news and Tajik media said he had flown to neighbouring Tajikistan.
Until that point, Mr Ghani had not made an official statement confirming a power vacuum.
The world looked to both Mr Ghani and the whereabouts of Taliban founder Omar Baradar, who was preparing to head back to Afghanistan from abroad, according to the group’s spokesman, Suhail Shaheen.
Before the day was over, Mr Ghani appeared in a video message declaring the Taliban had “won”.
“The Taliban have won with the judgement of their swords and guns, and are now responsible for the honour, property and self-preservation of their countrymen,” he said on Facebook.
Declarations of victory by Taliban officials began trickling in.
“We have never expected to reach such a victory,” the Taliban’s deputy leader, Abdul Ghani Baradar, said in a video message shared on Twitter, congratulating his fighters and the nation.
“Now is the time when we will be tested on how we serve and secure our people, and ensure their good life and future to the best of our ability.”
But with mounting international pressure against them, how far a potential Taliban takeover of the country will differ from their last ruling stint has yet to be seen.