The Islamic State’s ‘caliphate’ shrunk by 12,800 km2 to 78,000 km2 between 1 January and 14 December 2015, a net loss of 14%, according to the latest estimates by the IHS Conflict Monitor team.
Losses in 2015 include large swathes of Syria’s northern border with Turkey, including the Tal Abyad border crossing, which was the group’s main access point to the Turkish border from their de-facto capital Raqqa.
Other substantial losses in Iraq include the city of Tikrit, the fiercely contested Beiji refinery complex, and a stretch of the main highway between Raqqa and Mosul, complicating the transfer of goods and fighters between the two cities.
The Islamic State’s most significant gains in 2015 came from their advance into western Syria via Palmyra, and the capture of Ramadi’s city centre. Both were achieved in a near simultaneous offensive in May 2015, but came at the expense of losing northern Syria to the Kurds.
The Islamic State redeployed fighters from its northern frontline with the Kurds in order to launch the offensives in Palmyra and Ramadi. This indicates that the Islamic State was overstretched, and also that holding Kurdish territory is considered to be of lesser importance than expelling the Syrian and Iraqi governments from traditionally Sunni land. In fact, geospatial analysis of IHS data shows that Islamic State activity outside areas it controls is heavily concentrated around Baghdad and Damascus, but much less so in Kurdish territory.
Syria’s Kurds are by far the biggest winners in 2015, expanding territory under their control by 186% to 15,800 km2. They have established control over nearly all of Syria’s traditionally Kurdish areas, and are the largest component of the Syrian Democratic Forces (SDF), which are being nurtured to form a key part of the US ground campaign against the Islamic State in 2016.
