Bulgarian hands and Bulgarian attacks

The strategic value of Yeles was fully appreciated by the Bulgarian commanders, and heavy reinforcements were evidently poured into the Yardar trench at that point. All efforts of the Allied armies failed to achieve their purpose; Yeles remained in Bulgarian hands and Bulgarian attacks on the poorly equipped Serbs defending Katchanik gorge proceeded without serious interruption. When it became apparent that the Katchanik position could not long be held, the Serbian armies at the north and east fell back toward the Ipek basin, while those farther south retired on the Monastir basin.

All danger to the Teutonic occupation of the Morava- Yardar trench north of Yeles was thus removed, and the remainder of the campaign consisted in squeezing the remnants of the shattered Serb forces and their Montenegrin allies westward through Albania and southward through Montenegro to the sea; and in driving the Anglo-French army and the Serbs near Monastir back upon the Saloniki defenses. The first of these movements progressed with exceeding slowness because of the difficult character of the country; and the terrors of the Serbian retreat over rugged mule paths and through wild mountain gorges in the cold and snow of winter can scarcely be imagined. But from the standpoint of strategic geography the second movement alone merits special consideration.

Yardar valley toward Veles

When the French and English pushed up the Yardar valley toward Veles they seized as their base for a great armed camp the triangle of mountainous ground lying between the Yardar Biver and one of its tributaries known as the Tsrna, the latter a stream which must not be confused with the river of same name emptying into the Trinok in northeastern Serbia. The position had certain topographic advantages which enabled it to be held for a long time in the face of superior forces; but suffered from one serious disadvantage which ultimately compelled its evacuation. Both the mountain ridges and the river trenches afforded admirable natural defenses. The gorge of the Tsrna is steepsided and the stream unfordable.

The only practicable bridge, a few miles above the river’s mouth, was destroyed by the French after they had failed in an effort to move westward and join the Serbs, who were fighting at Babuna Pass to prevent the Bulgars from getting into Monastir basin. For defensive purposes the larger Yardar Biver, protecting the east side of the triangle, was strategically important, because it is both wide and unfordable and its valley is steepsided,—in one place a veritable gorge.