This obliged the cavalry division, which had been cooperating with the Serbian center and was driving the Austrians toward Leshnitza, to retire along a line from Metkovitch to Brestovatz. Naturally the advance of the Austrians from Shabatz was endangering its right flank. Moreover, a reenforced column of Austrians also appeared before it. But this opposing force did not press its advance. Meanwhile, on the same day, August 18, 1914, the Austrians were reenforcing their position on the Tzer ridges. They had also strongly fortified the height of Rashulatcha, which lay between the heights of Tzer and Iverak, whence they could direct an artillery fire to either field of activities. But the difficulties which the Serbians operating along the Iverak ridges were meeting also hampered the Serbians who were attempting to sweep the Austrians back along the Tzer ridges. If they advanced too far they would expose their flank to the Austrians over on Iverak. As a general rule, it is always dangerous for any body of troops to advance any distance beyond the general line of the whole front, and this case was no exception. However, though delayed, this division did advance. Oxen were employed in dragging the heavy field pieces along the trails over the rocky ridges. With savage yells the Serbian soldiers leaped over the rocks, up the jagged slopes of Kosaningrad. Again they had fallen back on their favorite weapons, bayonets and hand bombs. The Austrians put up a stout resistance, but finally their gray lines broke, then scattered down the slopes, followed by the pursuing Serbians. Having gained possession of Kosaningrad Peak, the Serbian commander next turned his attention to Rashulatcha, which, in conjunction with the Serbians over on Iverak, could now be raked by a cross artillery fire. He had previously left a reserve force behind at Troyan. This he now ordered to reenforce his left, which had been advancing along the southern slopes of the Tzer range. This force he now directed against the heights, but the movement was not vigorously followed up. Over on Iverak the Serbians had succeeded in making some headway. Forming into two columns, this wing marched out and attacked the Austrians at Yugovitchi and succeeded in driving them from their trenches. But immediately the Austrian artillery on Reingrob opened fire on them, and they were compelled to dig themselves in. And late that night, August 18, 1914, the Austrians delivered a fierce counterattack. But night fighting is especially a matter of experience, and here the Serbians with their two Balkan campaigns behind them, proved immensely superior. They drove the Austrians back with their bayonets.