Capturing Kunduz was the most important victory for the Afghan Taliban since their regime was ousted by US-led forces in late 2001.
It was the first provincial capital to end up in Taliban hands since the invasion.
The fall of Kunduz, however fleeting, represents a win-win for the Taliban.
The insurgents were pushed out of most of the city in a military counter-offensive three days later - but they left with both booty and publicity.
Taliban fighters emptied the coffers of banks in Kunduz, seized scores of new weapons, including armed vehicles, and also gained a great propaganda victory.
Pictures of Taliban fighters hoisting their trademark white flags in the city's squares and main buildings have been circulating on social media all over the world.
The seizure of one of Afghanistan's most strategic and richest cities has also increased the prestige of the new Taliban leader, Mullah Akhtar Mansour. Those within the insurgent group will see him as someone who can deliver impressive victories on the battlefield.
Victory also reasserts Taliban control vis-a-vis the Islamic State group, which has been challenging the Taliban's supremacy in many parts of the country.
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The Afghan security forces have performed well in holding ground and defending towns and administrative centres across the country. But the fall of Kunduz has exposed their vulnerabilities.
The fact that a few hundred Taliban fighters defeated thousands of Afghan security forces - up to 7,000 according to some reports - is also embarrassing for the central government in Kabul. This is especially so given that the fall of the city coincided exactly with the first anniversary of the National Unity Government's formation.
Bad governance in Kunduz has been a key problem. Incompetence and intimidation by some local officials have alienated many in the province.
Rivalries and disagreements between different civilian and security officials, meanwhile, have weakened institutions and deteriorated security.
Nepotism and patronage are allegedly common factors in making many important appointments.
As a border town with plenty of trade and taxation activity, obtaining a posting in Kunduz has been a top priority for corrupt officials. The province is also a major transit route for the smuggling of Afghan drugs to Central Asia and Russia.
'Huge strategic significance'
A combination of a lack of strategy, poor co-ordination and incapability led to the quick collapse of the city.
Reports say that several thousand residents of Kunduz left. Hospitals were overwhelmed, with hundreds of people already injured.
The Taliban used loudspeakers in mosques to urge people to carry on as normal and open their businesses.
Reports say the Taliban collected boxes of energy drinks from shops for their fighters.
Kunduz has a huge strategic significance as it is considered a gateway to Afghanistan's northern provinces and shares a border with Tajikistan, Afghanistan's Central Asian neighbour.
The Taliban already control huge chunks of Kunduz province's rural areas, where the majority of the population live.
They are the dominant militant group in the province, with an estimated 2,000 fighters. But there are also reportedly hundreds of foreign fighters associated with al-Qaeda, so-called Islamic State and the Islamic Movement of Uzbekistan (IMU).
According to Afghan officials, members of several jihadi groups from across the region have been present in the province, including Arabs, Uzbeks, Chechens, Uighurs and Pakistanis.
As one of the last strongholds of the Taliban before the fall of their regime in 2001, Kunduz has a special importance for the Taliban.
Until its recent fall, the city had been under Taliban siege for almost a year.
For the insurgents, it is not a battle for one city alone but part of a major strategy to hold it and use it as a regional hub, a sanctuary and a base for operations.
The way the Taliban behaved while in control of the city, even if it was for just a few days, will demonstrate how far the group has changed since the fall of their regime in 2001.
It was also a test for them to show if they are just a warring faction of mostly rural fighters or a group that knows how to govern and deal with the complexities of an urban centre.
Capturing Kunduz was a change in Taliban strategy. Previously, they were not keen on taking major cities, firstly because they could not fulfil the responsibilities of running them and secondly because they thought it would expose them to targeted attacks, especially by drones.
But the Taliban might have been inspired by the Islamic State group in Iraq and Syria, which found operating in cities easier than in rural areas. The increased risk of civilian casualties in an urban environment means major counter-attacks against them from outside forces are more difficult.
Given the number of attacks the Taliban have been carrying out all over the country, Afghan security forces are already overwhelmed and overstretched.
The Taliban are now trying to open multiple fronts to divert the attention of the Afghan military from Kunduz and stretch them thin.
They also want to expand their control further by linking up areas they occupy in different parts of the country.
This has been the bloodiest year in the 14-year-old Taliban insurgency. Both Afghan troops and civilians have suffered the highest number of casualties in 2015.
Recapturing Kunduz was also a test for Afghanistan's foreign allies, especially the US, with which it signed a bilateral security agreement (BSA) in 2014.