Siege of Deir ez-Zor (2014–2017)

Siege of Deir ez-Zor
	Part of the Deir ez-Zor Governorate campaign of the Syrian civil war
	; Syrian Republican Guard T-72 tank in Deir ez-Zor
Date	14 July 2014 – 17 November 2017 ; (3 years, 4 months and 3 days)
Location	Deir ez-Zor, Deir ez-Zor Governorate, Syria
Result	Syrian government victory
Territorial; changes	IS besieges Syrian government forces in July 2014 (after expelling Syrian rebel forces from the province); IS military forces split the government-held Deir ez-Zor pocket in January 2017; Syrian government forces reach the Brigade 137 base, thus meeting with besieged Syrian Arab Army forces, and lifting the IS siege of the city; Siege of the government-held airbase ends on 9 September 2017, with all surrounding points recaptured by 10 September; Syrian government forces captures IS-held parts of the city on 17 November;
Belligerents
Syrian Government; Hezbollah; PMF-affiliated militias; Russia (Sep 2015 – Nov 2017)	Islamic State
Commanders and leaders
Issam Zahreddine †; (Republican Guard); Yarob Zahreddine; (104th Airborne Brigade); Hassan Mohammad; (17th Division; since July 2016); Mohamed Khaddor; (17th Division; until July 2016 & returned Jan. 2017); Omar al-Alawi (WIA); (Head of Deir ez-Zor NDF); Mudar Makhlouf; (Military Intelligence militia commander); Sergei Surovikin; (Russian forces commander); Valery Asapov †; (Syrian 5th Corps commander)	Gulmurod Khalimov †; (ISIL war minister); (Emir of Deir ez-Zor); Abu Khadijah al-Masri †; (ISIL Governor of Deir ez-Zor); Amer al-Rafdan †; (ISIL leader of Deir ez-Zor); Abu Hamza al-Ansari †; (ISIL Deir ez-Zor emir); Abu al Faruq †; (ISIL Deir ez-Zor commander); Abu Jandal al-Kuwaiti †; (ISIL top commander); Abu Hadhefah al-Maghrabi †; (ISIL field commander)
Units involved
Syrian Armed Forces Syrian Arab Army Republican Guard 104th Airborne Brigade; Qalamoun Shield auxiliaries; ; 17th Reserve Division 137th Mechanized Brigade; ; ; Syrian Arab Air Force; National Defense Forces (Deir ez-Zor branch) Arab Socialist Movement forces; Loyalist tribal militias; ; Local Defence Forces Qamr Bani Hashim Division; ; ; Military Intelligence Directorate Military Security Shield Forces; Forces of the Fighters of the Tribes; ; Sootoro Russian Armed Forces (since Oct. 2015) Russian Air Force; Russian Navy; Special Operations Forces; ;	Military of the Islamic State Wilayat al-Khayr; ;
Strength
4,000–5,000 (besieged, pro-gov. claim); 10,000–15,000 (Relief force, Syrian Army claim)	5,000–15,000 (Syrian Army claim)
Casualties and losses
460–970+ killed	1,430–1,970+ killed
	329–500+ civilians killed, ~400 kidnapped

The siege of Deir ez-Zor was a large-scale siege imposed by the Islamic State (IS) militant group against several districts in the city of Deir ez-Zor held by the Syrian government military forces, in an attempt to capture the city and secure full control of the Deir ez-Zor Governorate. The ISIL siege of the city lasted for almost 3 years and 2 months, after which the Syrian Army launched a successful offensive that fully recaptured the city nine weeks later.

In April 2014, IS launched a large-scale offensive against Syrian rebel forces in Deir ez-Zor province. This resulted in the total defeat of rebel groups in the area, and IS gained control of almost all of Deir ez-Zor Governorate in July 2014. Syrian government forces remained besieged in the pocket of territory they continued to control. On 10 September 2017, the siege was fully broken by Syrian government forces. After another two months of fighting, the Syrian Arab Army captured the IS-held parts of Deir ez-Zor city and its environs, by 17 November 2017.