Mountainous region bordering the Western Morava

It was supposed that when the Austro-German forces reached the higher mountainous region bordering the Western Morava valley and it became difficult if not impossible to bring up their heavy guns, the rate of advance would become even slower than before. The fact that the advance was actually accelerated has been interpreted to mean that the failure of Serbian supplies weakened the defense more than the unfavorable local topography injured the plans of the offensive. The Teutons moved rapidly across the Western Morava, and the Serbian army took np a position running eastward along the mountain crests south of the valley, then southward along the ridge west of the Morava-Vardar trench, and southwestward across the Katchanik gorge.

It will immediately appear that the Katchanik position was the strategic key to this entire battle front. In the rear of the Serbian armies facing north and east, runs the straight subsidiary trench formed by the Lepenatz valley, Kosovo Polye, and the Ibar valley. The gateway to this trench is the narrow Katchanik gorge. A railway from Uskiib runs through the gorge to Mitrovitza at the north end of the Kosovo Polye, thereby more than doubling the strategic value of the depression. If the Bulgarian forces already in possession of tiskiib should succeed in breaking through the Katchanik gorge into the plain of Kosovo, they could strike north and east against the rear of the Serbian armies and convert retreat into disaster. Little wonder, then, that the “Katchanik Pass” figured so prominently in the war despatches during this period!

Key to the Serbian position

But if Katchanik was the key to the Serbian position, Yeles was the key to Katchanik. Should the Anglo-French troops coming up the Yardar from Saloniki capture Yeles and debouch into the triangular lowland to the north, they would take in the rear the Bulgarian army trying to break through the Katchanik position. It would not be necessary for the Anglo- French force to enter the Lepenatz valley; the mere threat of enclosing the Bulgarians in the valley between the Serbs up at Katchanik and their allies down at the valley mouth would be sufficient to bring the Bulgars out of the trap in order to fight on the lowland, where, if defeated, they could retire northeastward into a region fully under their control. The threat would become imminent the moment Yeles fell to the Allies. Such were the topographic relations responsible for the rather striking fact that an Anglo-French attack upon Yeles relieved the pressure upon Serbian forces in the mountains far to the north.