But it was in the Syrian town of Kobani that the Islamic State suffered its worst single loss - more than 1,000 militants killed - and much of its heavy weaponry and vehicles destroyed. The January defeat followed five months of fighting by mostly Kurdish ground forces and coalition airstrikes that left about 70 percent of the town in ruins and sent tens of thousands of its residents fleeing over the nearby border into Turkey. After the loss of Kobani, signs of fissures within the IS group have emerged.