2014 Eastern Syria offensive
The 2014 Eastern Syria offensive was an offensive launched by the Islamic State (ISIL or IS) against government-held military installations in eastern Syria during the Syrian Civil War, after expelling the Syrian rebels from the region. The offensive is considered to be the largest military attack against the Syrian government launched by ISIL since its establishment.
Source: Wikipedia — 2014 Eastern Syria offensive (CC BY-SA 4.0)