By this time reenforcements had arrived from Saloniki, so he began moving across the plain through Negotin and Kavadar to the Tcherna. This stream, though narrow, was deep and unfordable. It could be crossed only in one place, by a small plank bridge, at Vozartzi.
On November 5, 1915, the French troops began crossing this bridge and scaling the heights before them, some of whose peaks towered fully a thousand feet above the river. And here it was that they first heard the booming of the Serbian guns, on the other side of the ridge.
Sarrail now advanced his men northward, along the west bank of the Tcherna, and next day he delivered an assault on the Mount of the Archangel, ten miles below Vozartzi. Here was the center of the Bulgarian positions, and here their lines must be pierced, if Babuna Pass was to be reached.
But not only was this position well fortified, but the Bulgarians were in superior force to the French. Moreover, as soon as Todoroff heard of what was going on, he hurried reenforcements to the Bulgarians on Mount Archangel. And this Sarrail knew; yet, without hesitation, he began the assault.
At the first attack the Bulgarian advance lines were driven out of the villages at the base of the mountain. The French continued their advance, and on November 10, 1915, they began a circling movement which resulted in the Bulgarians being squeezed out of Sirkovo, a village some distance up the mountain.
But by this time the Bulgarian reenforcements were beginning to arrive, and by the end of the second week of the month they began to take the offensive. They now had 60,000 men; against this force it was obviously impossible for the French to make any further headway.
The Bulgarian commander now showed that it was his intention to circle about the French, cut off their retreat by destroying the wooden bridge over the Tcherna in their rear, then pin them up against the mountain and pound them until they surrendered, all of which might have been accomplished by a more skillful general.
For three days a violent battle raged, in which the fate of the French army more than once hung in the balance, but superior military skill counted in the end. Possibly, too, the hearts of the Bulgarian soldiers were not in this fight, for the Bulgarian people have an almost reverential respect for the French. At any rate, they did not show here the same qualities that so distinguished them in the war against the Turks. At the end of the third day their lines began wavering, then broke. So completely were they routed that the French were compelled to bury nearly 4,000 of the dead they left behind. So close had the fighting been that at times the Bulgarian infantry charged the French positions to within a dozen yards, but in the last moment lacked the dash to carry them through the machine-gun fire and into the French ranks. At such moments the French would countercharge, whereupon the Bulgarians would turn and flee. Had the French been only a few thousand men stronger, they could have followed up their advantage, completely routed the Bulgarians, pushed their way across the mountains to Babuna Pass and so relieved the Serbians, as well as closing the gap through which the Bulgarians were yet to penetrate into Macedonia.