After seizing power in a rapidly summoned conclave, he proceeded to consolidate his hold over the movement, deflect attempts by the pro-Taliban clergy (ulema) to question his authority, co-opt or eliminate dissidents, renew the Taliban's war strategy and defy all efforts to maneuver the Taliban into peace negotiations.
To achieve all of this, Mansour drew on a rich repertoire of stratagems.
These ranged from doling out money and jobs in the Taliban shadow government to sweet-talking disaffected cadres, bribing clerics to give favorable pronouncements and playing for time whenever a problematic issue presented itself.
Although the Taliban movement experienced some factionalism
during Mansour's period, the situation could have been much worse had it not been for Mansour's hyperactive politicking.
Challenges for new leader
On Wednesday, the Afghan Taliban announced it had appointed Mawlawi Haibatullah Akhundzada as its new leader.
Being leader of the Afghan Taliban movement must be one of the most daunting jobs in the world. The first thing he will have to do is convince the rest of the movement of his legitimacy.
He has to demonstrate that he is a worthy candidate, is pious and a good Mujahid and that he has been selected according to Islamic law or Sharia, or at least to the Taliban's reading of it.
If he can do all this, then he can claim the unquestioning obedience that has been the prerogative of the movement's leaders. Not long after Mansour took over, he had the Cultural Committee publish a biographical sketch to highlight his leadership qualities.
The most pressing external challenge for Haibatullah will be to manage the relationship with Pakistan.
Taliban leaders tend to work on the assumption that they need to be tolerated by the Pakistan authorities, so they can use Pakistan as a rear base for their jihad in Afghanistan. The Afghan Taliban used to calculate that as long as they refrained from military action on Pakistan territory they would be left alone there.
Over the past six months, the Pakistan authorities have told the Taliban that the rules have changed. The Taliban must negotiate with the Kabul government or be prepared to face unspecified consequences.
Mansour, until the end, doggedly defied this pressure, by refusing Taliban officials permission to participate in talks, but offering a series of excuses and time-wasting tactics.
Haibatullah needs to reassess Pakistan's seriousness about getting the Taliban into talks and he will have to divine whether the Taliban really will face any consequences if they continue Mansour's approach of staying aloof from Pakistan-brokered negotiations.
Marketing the Taliban
Haibatullah has to take decisions on how to deal with the international jihadi networks, in particular Al Qaeda and ISIS, both of which are active in Afghanistan and Pakistan.
Mansour, like so many in the Middle East, saw in ISIS both a threat and an opportunity. ISIS have tried to challenge the Taliban's monopoly over leadership of the Afghan jihad. Mansour proved ruthless in pushing back against them in fully fledged military operations launched by the Taliban.
The Taliban's hard line stance against ISIS helped them make overtures to countries in the region. The Russians have claimed to have contacts with the Taliban, and the Iranian stamp in the passport Mansour traveled on is symbolic of Mansour's efforts to get the Iranians to provide backing to the Taliban.
But if anything, ISIS is looking weaker in Afghanistan than it did a year ago.
Thus Haibatullah will have to look for new ways to market the Taliban as a high potential anti-ISIS force worth supporting. But with Al Qaeda, the leader faces almost the opposite problem.
In accepting the oath of allegiance from Ayman Al Zawahiri and Al Qaeda,
Mansour exposed himself and his movement to having failed to learn the first lesson of the 9/11 era -- that hosting international terrorist groups plotting actions against the U.S. can attract terrible retribution.
Haibatullah will try to maintain the Taliban's reputation for being an uncompromising jihadi organization, for which alignment with Al Qaeda is useful, while he will be wary of alienating the Taliban base, many of whom are suspicious of the presence and role of the Taliban's foreign fighters.
And of course Haibatullah will be trying to make sense of the U.S. airstrike in Pakistan, which killed Mansour. Was it a once off operation or have the Americans decided to go after the Taliban leadership in Pakistan?
Understanding this is a life and death matter for Haibatullah. He will have to work out where it is safe for him to base himself and stay ahead of the drones.
Regrettably, probably the last issue in regional relations that the new leader will have to consider is how to deal with calls from the quadrilateral process countries (U.S., China, Pakistan and Afghanistan) for Taliban participation in peace talks.
Under Mansour, the Taliban treated this process as a diplomatic game -- how to look good while staying away and how to avoid provoking any power unnecessarily.
Mansour was determined to sustain the jihad and pursue the dream of re-establishing Islamic Emirate by force of arms and attrition.
Mansour's killing is the biggest indication which the Taliban have so far received to show that Mansoor's military ambitions were overly ambitious.
It remains to be seen how far that realization can take the new leadership towards the bitter pill of negotiating with the Kabul government.
Editor's Note: Michael Semple is a visiting professor at the Institute for the Study of Conflict Transformation and Social Justice, Queen's University Belfast. The views expressed here are solely his.