Operation Conquest or Operation Fatah was an offensive against the positions of the Islamic State (ISIL) in Mosul and the surrounding region. The offensive was a joint effort by the Iraqi government forces with allied militias, the government of Iraqi Kurdistan, local Assyrian Christian, Yezidi, Turcoman and Armenian militias, and US and UK air support and limited ground forces.
The aim of the operation, part of the military intervention against ISIL, was to set the conditions for an upcoming battle to push ISIL out of the second-largest city of Iraq, as well as the rest of the Nineveh Governorate.
The operation follows the Mosul offensive in 2015, which successfully recaptured parts of the region northwest of Mosul, but stopped short of breaching the city itself, for various reasons. The fall of Mosul to ISIL occurred between 4 and 10 June 2014.
The offensive began on 24 March 2016, near the Makhmur area of the Nineveh Province. Thousands of Iraqi troops had been deployed there in the previous weeks, setting up bases alongside Kurdish and US forces. While advancing westward toward the oil town of Qayyarah, Iraqi troops were reported to have recaptured several villages from ISIL, among them Al-Nasr, Garmandi, Kudila and Khurburdan, though it was later revealed that ISIL was still occupying Al-Nasr and the government forces were trying to capture it.
Around 4,000 soldiers, from two brigades of the U.S.-trained 15th Division of the Iraqi army, including Sunni tribal fighters (considered by Peshmerga commanders to be crucial to hold the traditionally Sunni areas), met stiff resistance. It was reported that they were attacked by suicide bombers as well as with mortars and machine guns, which stopped the advance for the time being. Warplanes of the U.S.-led coalition against ISIL launched multiple airstrikes on at least two locations. 200 U.S. Marines had set up a small outpost called Firebase Bell in the previous weeks. From there they provided artillery and targeting support for Iraqi forces. The presence of U.S. Marines became known after one of them was recently killed by the detonation of a roadside bomb. Kurdish Peshmerga forces didn’t take an active part, contenting themselves with holding the front line at what they consider the border of their territory.