When Syrian government forces circled the villages of Jebel Zawiya in 2011, Jamal Maarouf moved into action. A construction worker by training, he gathered seven men, and according to reports, set off to fight the advance.

Within months, Maarouf gained fame by becoming the first known rebel to shoot down a regime jet. In time, he would command thousands as one of two major strongmen in Idlib province. He paid his fighters a salary, offered them training, ran a prison in his village, and even established a nascent court system.

When FRONTLINE first met him in 2012, he was commanding the Martyrs of Syria Brigade, one of the largest factions of the Free Syrian Army, and preparing an attack on a government base at Wadi Daif. The meeting was featured in FRONTLINE’s Syria Behind the Lines.

A second meeting — in which Maarouf narrowly escaped a regime airstrike — was captured in FRONTLINE’s digital film The Bombing of al-Bara.

Two years later, with Islamic extremists threatening to capture hard-won rebel territory in the north, Maarouf has emerged as a key, albeit controversial, figure during an increasingly pivotal phase of the war.

In December, under threat from the extremist Islamic State of Iraq and Syria (ISIS), a hodgepodge of 14 religious and secular rebel factions elected Maarouf to head a new movement called the Syrian Revolutionary Front (SRF).

“We’re ready to fight every group that behaves like the regime,” Maarouf told FRONTLINE in Syria’s Second Front. “And if a group wants to use weapons against us and fight us and their goal is to steal the Syrian revolution, we will not hesitate to fight back.”

The election marked a change in fortune for Maarouf, who has been criticized by rivals as a warlord and “highway robber.” As the European Council on Foreign Relations noted in a recent policy brief:

By the end of 2013, he was looking like a spent force. Many of his colleagues had long taken to calling him Jamal Makhlouf, pinning him with the surname of Assad’s cousins who hold business monopolies in the country thanks to nepotistic corruption. Commanders frequently complained that Maarouf was more of a showman and warlord than a fighter, promising to participate in a particular battle, securing the funding for it from sponsors (mainly Saudi Arabia), and then withdrawing soon after the fight began after filming enough footage to upload to YouTube to boast of his group’s participation. It was a common complaint. Now, many of those same men speak with admiration of how Maarouf is personally fighting and how his men are pushing back ISIS with vigor.

Days after Maarouf’s election, the SRF launched and won its first major offensive against ISIS in the strategically important town of al-Atareb, near the border with Turkey.

As the SRF now looks to recapture even more lost ground from ISIS, it’s promising to abide by a far less brutal interpretation of Islam. Still, Maarouf is a devout man who says he’s fighting for a Syria “governed by the sharia laws.”

“We want Syria in the future to be governed by Islamic governance, where justice is brought to the oppressed and punishes the unjust whoever he is,” he told FRONTLINE.

In the past, Maarouf has voiced support for democracy. “Syria is for all Syrians,” he told FRONTLINE in 2012. “If the regime falls, we vow to protect all the peoples of Syria. Only killers will be held to account … No one should be excluded from society.”

The question ahead for the still-fledgling SRF is whether Maarouf — who is generally regarded as one of the opposition’s more moderate voices — can keep the peace between disparate ideological wings that rarely found consensus before the arrival of ISIS. Two fronts of the war may depend on it.