English: Map of the territorial gains made by the Kurdish YPG and their allied during the Northern Syria offensive (2015), dubbed Operation Rûbar Qamishlo by the Kurds. The Northern Syria offensive lasted from May to July 2015, which was comprised of the Al-Hasakah offensive (May 2015) , and the Tell Abyad offensive (2015) . The offensive was the largest offensive carried out by the YPG against the Islamic State of Iraq and the Levant , which saw the Kurdish-led forces capture 6,835 square miles (11,000 square kilometers) of land, and over 900 towns and villages from ISIL. By early August 2015, ISIL had lost over 10,000 militants in Northern Syria, in clashes against YPG and the FSA during their offensive operations. The outcome of the offensive was deemed to be one of the biggest defeats dealt to ISIL, with the recent Kurdish advances stripping ISIL of multiple strongholds it once controlled, as well as crucial supply routes to Turkey.