This month, Syrians at home and abroad had, for the first time in a long while, cause for national celebration. In the capital city of Damascus, and in immigrant enclaves around the world, jubilant Syrians cheered and waved flags in recognition of the one-year anniversary of the ousting of former president Bashar al-Assad. For decades, Assad’s dictatorial regime had inflicted death and destruction on civilians in its efforts to remain in power in the face of popular unrest. Over the course of Syria’s devastating civil war, which lasted from 2011 to 2024, hundreds of armed groups tried and failed to topple the Assad regime. The efforts inevitably collapsed because of the opposition’s lack of central authority and fragmented nature.

That changed in December 2024, when a coalition of armed opposition forces led by Hayat Tahrir al-Sham, or HTS, launched a surprise offensive that ousted Assad and ended a dynasty that had ruled Syria for fifty years. In the year since, Syria has undergone a flurry of rapid transformations that have brought cautious optimism along with the lifting of international sanctions and a stream of financial commitments to help the country rebuild. Many Syrians now cheer for HTS’s commander Ahmad al-Sharaa, who serves as the country’s interim president. 

The emergence of HTS, an offshoot of Al-Qaeda and until this year a US-designated terrorist organization, shocked observers with its speed and power, as did the group’s successful unification of more than a dozen armed factions. Many had assumed that the Assad regime was too big, and too powerful, to fail. “That turned out to be wrong,” says Aron Lund, who researches Syria at Century International.

From the beginning, Syria’s opposition forces were fragmented, consisting of a bewildering array of factions, cleaving and coalescing unpredictably

While HTS had controlled only a small portion of the country prior to 2024, it quickly overtook Assad’s weakened forces in an eleven-day offensive that culminated in the seizing of Damascus on December 8, 2024. One year later, the factors that contributed to HTS’s rise are worth revisiting, says Lund, who investigated patterns in Syria’s fragmented insurgencies with the support of The Harry Frank Guggenheim Foundation. For his research project Insurgent Fragmentation and State Attachment in the Syrian Civil War, Lund traveled to Turkey, Jordan, and Lebanon between 2018 and 2020 and interviewed fighters and commanders to study how Syrian armed groups had united and splintered since the onset of the war. 

Syria’s civil war began in 2011 following a government crackdown on popular protests that emerged as part of the Arab Spring. From the beginning, Syria’s opposition forces were fragmented, consisting of a “bewildering array of factions, cleaving and coalescing unpredictably,” says Lund. As Russia and Iran bolstered the Assad regime, other foreign powers like the United States, Qatar, Turkey, and Saudi Arabia supported the expanding matrix of opposition insurgents. Several attempts to unify them, often under the moniker of the Free Syrian Army, ultimately failed. 

In his research, Lund found that the successful unification of rebel groups required some degree of leadership and coercion. Insurgents that came together around a single, dominant central faction had a better chance at integrating, compared to alliances of equals. Lund observed three key factors that contributed to this effect.  

First, the dominant coalescing faction required a strong ideological bent, which, in the Syrian context, tended toward Islamist ideology. Religious conviction and shared beliefs brought disparate bands together in a widely diverse country that remains fractured along tribal, religious, and regional lines—a fact leveraged by the Assad regime and opposition forces alike to divide people and accrue supporters.

These dominant groups “relied on a core of people who were already ideologically indoctrinated and then brought others into that community, and that allowed them to expand beyond the local or tribal base,” one former Islam Army commander told Lund in 2018. While the Obama administration had hoped to cultivate a rebel leadership that was secular and nonextremist, it was the powerful Islamist factions that were ultimately able to attract large followings of Syrian rebels and crush their rivals. 

The rebel organizations that did this most effectively were the Islamic State, or ISIS, and the Nusra Front, an offshoot of Al-Qaeda that later rebranded into Hayat Tahrir al-Sham. ISIS gained global notoriety for its violent interpretation of Islam. Similarly, the Nusra Front and HTS’s commander, Abu Mohammed al-Jolani, gained support with the promise to unite Syria under Islamic law. He now stands as Syria’s interim president under his civilian name, Ahmad al-Sharaa. According to Lund, HTS members “were pretty extreme” in their promotion of violence against religious minorities in Syria, and against Western states in the early years of the war. 

HTS also embodied the second factor that, according to Lund’s research, enabled the emergence of a dominant faction: first-mover advantage. According to Lund, the most successful rebel unifiers had backgrounds in preexisting militant organizations or battlegrounds. This gave them the advantage of battle-hardened fighters and access to guns, money, bomb-makers, and safehouses. Leaders of both ISIS and the Nusra Front, for example, gained experience in Iraq’s extremist underground fighting US troops. Between 2014 and 2017, ISIS ruled over large swathes of territory in both Syria and Iraq using extreme violence until eventually being pushed out. Meanwhile, the Nusra Front endured by consolidating power and partnering with other Islamist factions. In 2017, the Nusra Front distanced itself from Al-Qaeda and rebranded as HTS.

The most sectarian, most hardline group is also the one that’s now in power and has an interest in preventing these massacres, just for basic stability and to manage relations with the West

HTS’s emergence as a rebel hegemon powerful enough to defeat the Assad regime came down to a third factor: having what Lund calls a “mean streak.” According to his research, Syria’s most effective militant rebel groups were ones that were willing to prey on other rebels, decimate competitors, and violently suppress subfactions. Indeed, by the time the Nusra Front rebranded as HTS, evidently in a bid to assuage Western powers and garner international support, leaders had successfully crushed foreign-led rebel groups and cannibalized its local Islamist competitors. In northwestern Syria, “HTS grew dominant within its own enclave and then it clearly led the way to seizing Damascus,” says Lund. 

Ultimately, what made insurgent organizations like HTS successful in dominating competitors over the course of Syria’s civil war was not conceptual dealmaking, consensus building, or foreign assistance, but instead strength, power, and discipline. “Without that hard coercive element, you don’t succeed in that environment,” concludes Lund. Now at the seat of power in Syria, President Sharaa—the former rebel leader who ascended by unifying insurgent factions through Islamist ideology, jihadi credentials, and bloodshed—endeavors to present a more toned-down image to the world in what Lund deems “ruthless pragmatism.” 

While President Sharaa has announced the dissolution of all rebel factions and their integration into Syria’s national defense forces, maintaining unity in the post-Assad world will no doubt remain a challenge. Not least because the factors and methods that helped Sharaa unify rebel factions and ascend to dominance in the context of civil war might now hinder him in the face of international scrutiny. “He wants Syria to be stable, and he doesn’t want anything to interfere with his project of gaining legitimacy with the United States and Europe and other countries,” says Lund.

Though Sharaa has pledged to unify Syria, urgent questions remain about how extreme his regime’s ruling doctrine will be, the fate of other opposition forces, and the treatment of religious minorities. The deadly massacre of 1,500 Alawites, a religious minority historically linked to the Assad family, in March has already tested his promises. “The most sectarian, most hardline group is also the one that’s now in power and has an interest in preventing these massacres, just for basic stability and to manage relations with the West,” explains Lund, who notes that calculation could later change.

Beyond Syria, Lund’s HFG-funded research provides an important framework for understanding how insurgent organizations compete and coalesce in the cutthroat theater of war. “In the Middle East and North Africa, you have plenty of conflicts where you have these factionalized insurgencies,” said Lund. For those seeking to understand, and perhaps influence, such rebellions in Libya, Yemen, Sudan, and beyond, Lund’s research arrives at a frank yet pragmatic assessment: ”What makes those groups succeed is also what makes them unpleasant.”

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