The Eastern Qalamoun offensive was a large-scale military offensive against Syrian rebel positions in the eastern Qalamoun Mountains of the Rif Dimashq Governorate launched by the Islamic State of Iraq and the Levant along a frontline of more than 15 kilometers in the region.^[5]

Quick Facts Date, Location ...

Eastern Qalamoun offensive (September–October 2016)
Part of the Rif Dimashq Governorate campaign of the Syrian Civil War
Date 3 September – 15 October 2016 (1 month, 1 week and 5 days) Location Eastern Qalamoun Mountains, Rif Dimashq Governorate, Syria Result Limited ISIL gains ISIL captures four hills Rebels recapture several positions[1]
Belligerents
Jaysh al-Islam Free Syrian Army Ahrar al-Sham Jabhat Fateh al-Sham Authenticity and Development Front Syrian Arab Republic[2] Syrian Air Force	Islamic State
Commanders and leaders
Harith Siwar (WIA)[3] (Eastern Qalamoun Jaysh al-Islam commander) Salih Nouman  †[4] (Eastern Qalamoun Jaysh al-Islam commander) Abdul Rahman Abu Mansour[5] (Al-Rahman Legion deputy commander) Abu Barzan[6] (Lions of the East Army deputy commander)	Unknown
Units involved
Free Syrian Army Al-Rahman Legion Southern Front Forces of Martyr Ahmad al-Abdo Lions of the East Army Sham Liberation Army	Military of ISIL Wilayat Dimashq
Strength
600–1,500 fighters[5][7]	Unknown
Casualties and losses
24 rebels killed (ISIL claim)[8] 1 MiG-23 crashed[2]	23–62 killed (rebel claim)[7][9]

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On 3 September 2016, ISIL sent two car bombs towards rebel positions in the mountains, but both were destroyed before they could reach their targets. Following this, ISIL forces stormed the rebel-held territory from three different axes, overrunning several positions and reportedly killing more than 20 rebels.^[8]

Three days later, an ISIL convoy was deployed as they launched a second assault in the area. During the clashes, the rebels destroyed an ISIL T-72, a bulldozer, and a ZU-23-2, the latter with a BGM-71 TOW missile.^[10] The next day, Jaysh al-Islam recaptured a hill near Dumayr from ISIL.^[11]

On 9 September, ISIL launched a third attack against rebel forces in the mountains. Rebels led by Jaysh al-Islam and various Free Syrian Army factions repelled the assault and dozens of ISIL fighters were killed.^[9] Hundreds of rebel reinforcements reportedly arrived in the region the next day.^[7] On 13 September, ISIL recaptured the three hilltops of Jabal Zubaydi, Tall Daba'a and Jabal al-Afa'i.^[1] On 14–15 September, rebels launched a counter-attack to regain Jabal al-Afa'i.^[12] On 17–18 September, ISIL forces launched a successful assault against rebel positions at Badiya, killing four and capturing forty defenders,^[13] while losing two vehicles in return.^[14] Heavy fighting between rebels and ISIL in the area was reported on 19 September, as the ISIL offensive entered its 3rd week.^[15]

On 21 September, Ahrar al-Sham and the Forces of Martyr Ahmad al-Abdo recaptured the Rajem al-A'ali area, giving them the control of 40% of the al-Afa'i Mountains, while a Syrian Air Force MiG-23 targeting ISIL crashed in the region.^[16][17] Rebel forces made further progress later that day, retaking several positions at Jebal Batra.^[18] The pilot of the crashed government jet landed in rebel territory in the mountains and as a result of a truce in the area, the rebels handed him over to the Syrian Armed Forces and reportedly received small arms and ammunition from government forces in return.^[2] By 23 September, the rebels were in control of 70% of Jabal al-Afa'i.^[19]

On 26 September, unknown gunmen attempted to assassinate Harith Siwar, commander of Jaysh al-Islam in the Eastern Qalamoun Mountains.^[3] On 29 September, ISIL forces launched a new attack in the eastern Qalamoun Mountains, leading to heavy clashes with the rebel defenders.^[20] In the night of 1–2 October, ISIL fighters stormed eastern Jabal al-Afa'i amid heavy fighting with FSA forces.^[21] Two days later, Jaysh al-Islam repelled another major ISIL attack on Jabal al-Afa'i and al-Naqab.^[22] On 9 October, 12 ISIL fighters and an unknown number of rebels were killed in clashes after an attack by ISIL on al-Khandaq and al-Naqab mountain.^[23] Five rebels were killed in clashes on the following day.^[24] On 15 October, rebels launched an assault on Kahil Tes and Mahol areas.^[25]

On 26 October, Syrian military bombarded areas under ISIL control in the region.^[26] On 2 November, clashes renewed between ISIL and rebels, concentrated in the area of Jabal al-Afa'i.^[27]

On 6 November, the rebels launched their own offensive,^[28][29] attacking ISIL positions. The rebels stated they had captured three checkpoints, with 7 ISIL fighters and 4 rebels being killed in the clashes.^[29] With the recent advances, rebels broke the siege imposed by ISIL on them in the region and had started advancing northwards to retake territory previously captured by the group.^[28]

On 29 December, FSA forces launched an offensive toward ISIL lines in the eastern Qalamoun and captured five villages.^[30]

• Al-Dumayr offensive (April 2016)