Protests against the Syrian government and violence had been ongoing in the Syrian city of Deir ez-Zor since March 2011, as part of the wider Syrian Civil War, but large-scale clashes started following a military operation in late July 2011 to secure the city of Deir ez-Zor. The rebels took over most of the province by late 2013, leaving only small pockets of government control around the city of Deir ez-Zor. Since late 2013, ISIS became increasingly involved in the battle, but retreated tactically in February 2014. Still, in April 2014, ISIS launched a massive offensive, taking over all rebel areas. Heavy fighting continued in the city over the following years between government troops and ISIS. By mid-November 2016, it was reported that since the start of the fighting in Deir ez-Zor city five years earlier, around 3,000 anti-government jihadists and 2,500 pro-government fighters had been killed. Government forces were besieged but remained in control of 40 percent of the city and the military airport. Units Rebel forces Free Syrian Army/SNC-aligned units The rebel units in eastern Syria were originally largely independent and unorganized, until many accepted the authority of the National Coalition for Syrian Revolutionary and Opposition Forces (SNC) in late 2012. The authority of the SNC remained mostly nominal, however, and by late 2013 this alliance already began to disintegrate again. 3rd Infantry Division 4th Infantry Division 5th Commando Division 7th Division 11th Division Liwa Jund al-Rahman Liwa Chouhada' Deïr ez-Zor Ahfad al-Rasul Brigade Liwa al-Khadra' Liwa al-Abbas Liwa al-Qadisiya Liwa al-Muhajirin ila Allah Lions of Al Jazeera Retribution Army Al-Tawhid Brigade Mujahideen and Islamists Over time, several units left the SNC alliance due to differences, and formed new, often more Islamist coalitions. Nevertheless, these new alliances generally remained allied with the council. Harakat Abna' al-Islam Jaysh Al-Tawhid (also member of the Syrian Islamic Front) Kata'ib al-Ansar Kata'ib al-Sa’iqa Jaysh Ahl as-Sunna wa-l-Jama’a (formed from former Authenticity and Development Front member groups) Liwa al-Athar Liwa Usud as-Sunna Liwa Ahl al-Raya Jabhat al-Jihad wal-Bina' al-Islamiyya (under command of the Islamic Court of Deir ez-Zor) Liwa Jaf’ar al-Tayyar Liwa la Ilaha illa Allah Liwa al-Hawaz, Liwa Ibn Qiam Liwa al-Risalla Liwa al-Tawhid al-Islami Liwa Othman bin Afan Liwa Ahfad Mohammad Liwa Sarayat al-Rasoul Liwa Sadiq al-Amin Tajamm’u al-Rachidin Brigade of al-Qaka Radical jihadists Besides the SNC and the allied Islamist coalitions, there were also number of radical jihadist groups active