Siege of Deir ez-Zor (2014–2017)

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's 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.

Source: Wikipedia — Siege of Deir ez-Zor (2014–2017) (CC BY-SA 4.0)