ISIS shocked the world in 2014 when it took over a large swath of territory across Iraq and Syria and declared a caliphate. The terrorist group’s territorial holdings were the basis for its so-called caliphate, and provided it will a major base of operations to conduct attacks across the world. After a five-year effort led by the US, ISIS’s caliphate was finally defeated in March 2019. The terrorist group has lost its territory — its so-called caliphate — it’s still estimated to have up to 18,000 fighters in Iraq and Syria.