following the expansion of the islamic state of iraq and levant in late 2013 and early 2014, isil forces launched a major offensive against the rebels in the province and the city of deir ez-zor, pushing out rebel forces and besieging government troops in deir ez-zory city. for more than three years, the syrian arab army managed to keep control of the western half of the city, while isil was in control of the entire eastern side of the city. during this time isil launched several offensives to capture the remaining parts of the city with limited gains.