Deir ez-Zor (Arabic: دير الزور, DMG Dair az-Zaur, Armenian Դեր Զոր Der Zor) is a city in eastern Syria. It is the capital of the Deir ez-Zor Governorate of the same name.
The city, located on the Euphrates, is surrounded by fertile soil on which grain and cotton are grown. Since oil was discovered in the region, the city has become a center of Syrian oil production since the mid-1990s. Another economic sector of the city was tourism, as it is located 85 kilometers from Dura-Europos and 120 kilometers from Mari.
The population was calculated at 293,916 in 2010. Deir ez-Zor is the sixth largest city in Syria. The majority are Sunni Arabs.
During the Roman Empire, an important trading post was located in the area of today's city on the long-distance route along the Euphrates between the Mediterranean and the Sassanid Empire. Roman fortifications on this route were Halabiya 50 kilometers northwest and Dura Europos to the southeast. After these stations were conquered by Queen Zenobia, the city belonged to Palmyra's dominion for a few years. The town was destroyed by the Mongols in the 13th century during the Mongol invasion. In Ottoman times, the town was called Deyrizor and was the headquarters of the Sanjak Zor.
From 1915 to autumn 1916, the town, which was then part of the 
		Ottoman Empire, became the site of a concentration camp as part of the 
		Armenian genocide. The Turkish commander ran a brothel with forced 
		Armenian prostitutes in the Catholic church. This was also the 
		destination of countless death marches with which the then ruling Young 
		Turks under Interior Minister Talat Bey managed to exterminate up to one 
		and a half million Armenians.
Despite strong regional resistance, 
		the town was conquered by the French in 1921. After the First World War, 
		France controlled Syria from 1922 to 1941 as a mandate territory and set 
		up a garrison here. After the French withdrew in 1946, Deir ez-Zor 
		became part of independent Syria.
After the breakup of the Egyptian-Syrian Union, there had already 
		been an unsuccessful coup attempt by Arab socialists (Nasserists and 
		Baathists) in Deir ez-Zor on April 2, 1962, in which the later head of 
		state Louai al-Atassi was involved.
In view of the fact that 
		numerous leading members of the Baath Party and Nasserists who took part 
		in the coup on March 8, 1963 came from Deir ez-Zor (e.g. Jassem Alwan or 
		Jalal as-Sayyid), the city's central market square was renamed March 8 
		Square. However, many of the Arab socialists from Deir ez-Zor fell 
		victim to internal Baathist purges in the decades that followed, such as 
		a faction that was sympathetic to the former Baath leader Akram 
		al-Haurani in 1965.
In the course of the civil war that began in 2011, the city was 
		occupied by government snipers and tank units on August 1, 2011. 
		According to opposition figures published by Al Jazeera, 25 people were 
		killed. The day before, the broadcaster reported heavy attacks with 
		artillery and anti-aircraft weapons.
In March 2012, the Free 
		Syrian Army withdrew from the city on March 20 after several attacks by 
		government troops. However, on November 22, 2012, the insurgents 
		recaptured parts of the city. The terrorist group of Islamist rebels, 
		which has also controlled a large part of the surrounding area since the 
		beginning of 2013 - the IS - wanted to rule the Deir ez-Zor governorate 
		on the basis of Sharia law. A district adjacent to Deir ez-Zor airport 
		was still under the control of government troops.
In mid-August 
		2014, activists reported that IS members had captured and killed 700 
		members of the regional Sheitat tribe, including 600 civilians. After 
		government troops recaptured large parts of the city in a counterattack 
		between September and November 2014 and flew attacks against IS 
		positions from Deir ez-Zor, IS terrorists carried out a suicide attack 
		on the airport on December 4, 2014. Government troops were able to repel 
		an IS offensive.
On January 15, 2016, IS began an offensive 
		against the besieged city. Part of the city was already in IS hands at 
		that time. At the end of January 2016, according to Russian reports, IS 
		gathered two thousand fighters to take the city completely; the Russian 
		air force flew attacks on IS positions. In the besieged zone itself, 
		there were deaths due to malnutrition. The UN World Food Programme 
		supported the area with food dropped from the air.
In May 2016, 
		government garrison troops counterattacked and, according to their own 
		statements, drove IS fighters out of parts of the city. A hospital in 
		which IS had taken medical staff hostage was liberated and more than 200 
		IS fighters were killed. It was not until September 5, 2017 that Syrian 
		troops, coming from the west, broke through the IS siege ring and 
		reported the capture of the city in early November 2017. One day later, 
		on November 4, 2017, at least 75 people were killed in a car bomb attack 
		in Deir ez-Zor, according to other sources more than 100 people.
There is the Deir ez-Zor Regional Museum and a large cultural center.
		
Al-Furat University, founded in 2006, is partly based in the city. 
		Its faculties of agriculture, science, arts, social science, education, 
		law, petrochemical engineering and medicine are located in the city, 
		while other faculties are located in neighboring districts. There are 
		also vocational schools and other post-school education institutions.
		
The local daily newspaper Al Furat is published in the city.
		The Armenian Genocide Memorial Church in Deir ez-Zor was destroyed by 
		ISIS in 2014. Before that, it had been a major Armenian pilgrimage site, 
		especially on the annual genocide commemoration day.
A well-known landmark in the city was the historic suspension bridge 
		over the Euphrates. It was built around 1930 and after the construction 
		of the road bridge it was only used for pedestrian traffic (Arabic: 
		الجسر المعلق). The suspension bridge was destroyed in civil war fighting 
		in early May 2013.
The city is located on the CFS Aleppo-Qamishli 
		railway line and is intended to be the head of a planned railway line 
		via Abu Kamal to al-Qa'im in Iraq. Due to the political situation, only 
		a few kilometers have been built so far.
Deir ez-Zor Airport 
		(IATA: DEZ) is located in the suburb of al-Jafra.