Three years ago today, US Special Forces killed Osama bin Laden in his Abbottabad compound. Occurring in the midst of the Arab Spring revolutions that were taking root, the death of al-Qaeda's leader seemed to represent a defining moment. Not only had the group lost its leader, its entire ideology was being discredited by regime changes occurring via peaceful protest, rather than violence.
In hindsight, this turned out to be a wildly optimistic forecast. As the Arab Spring faltered, al-Qaeda and like-minded groups have flourished, controlling territory and launching a steady stream of terrorist attacks.
In order to assess the influence of bin Laden's legacy in all this, it is worth considering how things have changed - not only in the Middle East, but also within al-Qaeda itself.
There have been huge shifts in the Middle East's political landscape in the past three years. Two of bin Laden's former foes - Libyan leader Muammar Gaddafi and Yemen's President Ali Abdullah Saleh - have both been deposed (with Gaddafi subsequently being murdered). In Egypt, bin Laden lived to see the resignation of another former adversary, Hosni Mubarak, but not the chaos that has ensued since.
However, the most significant development has been the outbreak of civil war in Syria. This conflict has led to the largest congregation of mujahideen fighters in any one theatre since the Afghan 'jihad' against the Soviet Union in the 1980s (the war that was so instrumental in boosting bin Laden's reputation in 'jihadi' circles). Syria has had a hugely reinvigorating influence on al-Qaeda, which acted opportunistically to gain significant amounts of territory and supporters there. Syria has also led a fresh generation of Westernersinspired to travel to a 'land of jihad' in defence of Muslims. While not all those who have gone to fight in Syria will pose a threat when they return to their country of origin, some will, extending the domestic terrorism threat by years.
Bin Laden was militarily experienced, theologically well versed enough to inspire others to die for his cause and pulled off the most remarkable terrorist attack in history on 9/11. No-one else alive today in al-Qaeda can match this, and international counterterrorism efforts mean that replicating it on a similar scale is now virtually impossible.
Significant change has also occurred within al-Qaeda itself in the last three years. The volume of US drone strikes against al-Qaeda's senior leadership in Pakistan has meant that the network is more decentralised than ever. The operational oversight that bin Laden's replacement, Ayman al-Zawahiri, has over the group is likely at an all-time low (something that bin Laden would also have found virtually impossible to avoid were he alive).
This has led to a fundamental shift in the way al-Qaeda is run. Last year, Nasir al-Wuhyashi, a trusted bin Laden aide and emir of al-Qaeda in the Arabian Peninsula, was appointed as al-Qaeda's general manager. This was the first time a senior leadership role had been handed to a member of a regional affiliate, rather than the core leadership in Afghanistan and Pakistan. A paper issued by Britain's Foreign & Commonwealth Office said that this signalled the demise of the "al-Qaeda core leadership" concept, as Wuhayshi's appointment showed that the leadership in Afghanistan and Pakistan "do not necessarily have a higher standing than any of the other AQ [al-Qaeda] groups". This is a significant shift from bin Laden's time.
Another change since then is that two more regional affiliates are formally part of the al-Qaeda network - the Al-Nusra Front (ANF) in Syria and al-Shabaab in Somalia. The creation of the ANF occurred months after bin Laden's death, as did al-Shabaab's integration into the al-Qaeda network (bin Laden had actually been dubious of the merits of formalising these ties). Yet now, in sheer weight of numbers, these new groups are actually al-Qaeda's two largest affiliates. These developments make al-Qaeda a very different proposition now than when bin Laden was alive.
However, al-Qaeda has not just gained affiliates since May 2011; it has also lost them. Its Iraq offshoot, the Islamic State of Iraq and al-Sham (ISIS), has been expelled over the carnage it has unleashed in Syria and its refusal to take guidance from al-Qaeda's senior leadership. This move has contributed to ISIS now becoming a regional competitor for influence among 'jihadi' groups.
According to the business intelligence group Five Dimensions Consultants, the emir of ISIS has sent a letter to several al-Qaeda affiliated groups asking that they pledge allegiance to him instead of Zawahiri. This has led to some success, with Egypt's Ansar Beit al-Maqdis subsequently agreeing to do so. ISIS's rise may threaten the group's overall position at the forefront of the violent movement.
Despite this, bin Laden's death has clearly not led to al-Qaeda's decline. Its presence has spread all over the world, with numerous countries blighted by its ability to inflict violence and suffering. Furthermore, al-Qaeda's ideology carries on inspiring Westerners to attempt attacks domestically. In these regards, bin Laden's legacy lives on.
Yet this should not mean that we disregard the importance of his death. Bin Laden was militarily experienced, theologically well versed enough to inspire others to die for his cause and pulled off the most remarkable terrorist attack in history on 9/11. No-one else alive today in al-Qaeda can match this, and international counterterrorism efforts mean that replicating it on a similar scale is now virtually impossible.
That does not mean that al-Qaeda no longer poses a grave threat. Clearly it does. But it does mean that, thankfully, bin Laden remains one of a kind.
Robin Simcox is a research fellow at the Henry Jackson Society, where he has contributed to several reports on al-Qaeda, including Al-Qaeda in the United States: A Complete Analysis of Terrorism Offenses, Al-Qaeda's Global Footprint: An Assessment of al-Qaeda's Strength Today and Islamist Terrorism: The British Connections.
The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera's editorial policy.