Syria’s assorted, fragmented, and decentralized militant opposition movement exists under two general umbrellas – those brigades that affiliate themselves under the wider umbrella of the Free Syrian Army (FSA) which was first announced on July 29th 2011 by defected military officers, and those who are unaffiliated with the FSA and operate under the umbrella of the jihadist or groups which intend to do jihad in Syria. Although brigades in both umbrellas are made up primarily of Sunni fighters and Islamists, jihadists are often differentiated with jihadist brigades through their more conservative Islamism and employment of symbols such as the flag of the Islamic creed (shahada) rather than the green and white Syrian flag that is used by FSA brigades. What follows bellow is a brief overview of seven of the most visible Syrian rebel brigades under both the FSA and jihadist banners .
 

Free Syrian Army

The Farouk Brigade (Liwa al-Farouq) is a militant brigade in Syria’s opposition that fights under the umbrella of the Free Syrian Army. It was formed in August 2011 and is estimated to have 7,000–10,000 armed fighters. The brigade has been led by Abu Sayeh Jenaidi since October 6, 2012, when he replaced Lieutenant Abdul-Razaaq Tlass, the nephew of former Syrian defense minister Mustafa Tlass. 
 
The Farouk Brigade is based mostly in Homs, with some presence in Daraa and also in parts of Idlib near the Turkish border. It has primarily fought in Hama and Homs, most notably during the February 2012 siege of Baba Amr. 
The Farouk Brigade’s moderate Islamist orientation has caused some clashes with other rebel groups. In early September, for example, the group claimed responsibility for killing Islamist extremist Abu Mohamed al-Shami Abu al-Absi, who was known to have links with Jabhat al-Nusra. In January 2013, a top commander of the Farouk Brigade was assassinated by other rebels who many believe had links to Jabhat al-Nusra.
 
The Tawhid Brigade (Liwa al-Tawhid) is a rebel militant brigade that operates under the banner of the Free Syrian Army. The brigade was formed in July 2012 in Aleppo and its countryside and is made up of estimated 7,000–10,000 fighters. 
 
The Tawhid Brigade is organized into three sub-brigades—the Fursan al-Jabal Brigade, the Darret al-Izza Brigade, and the Ahrar al-Shamal Brigade—and is made up of 195 battalions. It is led by Abdul-Aziz Salameh and Abdel Qader Saleh, both of whom are from the Aleppo countryside. The brigade is known for its conservative Islamist orientation. It has mostly been involved in the battle of Aleppo, which began in August 2012.
 
The Idlib Martyrs’ Brigade (Liwa Shuhada’ Idlib) is a rebel militant brigade that operates under the banner of the Free Syrian Army. It was formed in March 2012, and its total number of fighters is unknown but is thought to be greater than a few thousand. The brigade only operates in Idlib and its countryside. 
 
The Idlib Martyrs’ Brigade was headed by Basel Eissa until he was killed in the city of Harem in the Idlib countryside on November 5, 2012. It is unclear who the present leader is. The brigade has an Islamist orientation and has been involved in battles to liberate the Idlib Province, especially areas near the Turkish border, since the summer of 2012.
 
The National Unity Brigades (Kata’ib al-Wahda al-Wataniya) are small rebel brigades that operate under the banner of the Free Syrian Army. They were formed in August 2012 and are most active in the Damascus countryside, Idlib, Suweida, and Hama and its countryside. They are estimated to have a few hundred members. 
 
The brigades have a secular orientation and are most well-known for the inclusion of minorities such as Christians, Druze, and Ismailis. Unlike the Islamist brigades, most of the National Unity Brigades have secular or nationalist names, including the Yusuf al-Azmah Brigade, named after a famous Syrian Kurdish leader, or the Abd al-Rahman al-Shahbander Brigade, named after a Syrian nationalist who fought against French occupation. The brigade has not yet been involved in any major battles.
 
The Salah al-Din al-Ayyubi Brigade (Liwa Salah al-Din al-Ayyubi) are small rebel brigades that operate under the banner of the Free Syrian Army and the Supreme Kurdish Military Council. They were formed in May 2012 and are estimated to have a few hundred fighters. They are the largest Kurdish brigade in the Free Syrian Army but also contain Arabs and Turkmen among their ranks. They are led by Captain Bewar Mustafa a Kurdish defector from the Syrian army and are mostly active in Aleppo and its countryside.
 

Jihadists

The al-Nusra Front (Jabhat al-Nusra) is a militant rebel jihadist brigade fighting in Syria’s opposition that is widely believed to have links to al-Qaeda in Iraq. It began holding meetings in Syria in October 2011, but the group is not new as many of its members have existed as a part of al-Qaeda in Iraq prior to this date. Its leader, Abu Muhammad al-Julani, came to Syria from Iraq in 2011. Its first video statement was released on January 24, 2012. 
The brigade is mostly based in Aleppo and Deir Ez-Zor, but it also has a presence in the Damascus suburbs and Homs. It is estimated to have approximately 5,000–7,000 fighters. 
 
Al-Nusra is known for its suicide operations at checkpoints and regime outposts. It has also claimed responsibility for the assassination of journalist Mohammed al-Saeed on December 23, 2011, one of the first suicide bombings during the civil war. The group’s goal is the creation of an Islamic state with a Salafi interpretation of Islam throughout all Muslim lands and the establishment of a global caliphate with the Quran and the statements of the Prophet as the only sources of law.
 
Ahrar al-Sham is a militant rebel jihadist brigade fighting in Syria’s opposition. It is led by an Idlib-based “emir” known as Abu Abdullah, although it is often represented by its military commander for the Idlib Province, Abul-Hassan. It was formed in late 2011 and early 2012 and is based mostly in Idlib Province, although it is also present in Hamah and Aleppo. It is estimated to have thousands of members, although the exact number is unknown. 
 
The brigade gained fame when it rescued NBC journalist Richard Engel and his crew from a Syrian regime kidnapping in December 2012. 
 
Ahrar al-Sham also contains nonmilitary wings that provide for children’s education, aid distribution, and sharia courts. It was one of the first brigades to use roadside bombs and IED attacks. The group seeks to remove the Assad regime and replace it with a Salafi Islamic state in Syria. Unlike other jihadist organizations, it does not seek a pan-Islamic global caliphate.
 
Suqoor al-Sham is a rebel militant jihadist brigade fighting in Syria’s opposition led by Ahmed Abu Issa. It was formed in November 2011 and is estimated to have between 4,000–5,000 armed fighters. The brigade is mostly based in the Idlib Province. 
 
Suqoor al-Sham is known for its Salafi orientation, and its ultimate goal is the establishment of an Islamic state in Syria with laws stemming from the Quran and the sayings of the Prophet. It does not explicitly seek a global caliphate, unlike Jabhat al-Nusra and other groups. It is known for its suicide car-bombing operations.