Up in the northwest the Austrians also held a narrow strip of Serbian territory, along the Drina from Kuriachista up, but with this small exception they were confined to their side of the river until the triangular tract in the northeast of the Matchva Plain was reached, previously mentioned.
Along the Save from Parashnitza to Shabatz they had also attempted a southward movement, where they were supported by five river monitors. During the period of comparatively little activity which now followed the Serbians were much worried by these monitors, which patrolled up and down the river at night, throwing their searchlights on and exposing the Serbian trenches. Then, too, they could hurl bombs into the Serbian positions with almost absolute impunity, for whenever the Serbian shells struck the heavy armor of these river fortresses they rolled off harmlessly.
On the night of October 22, 1914, the Serbians sent some mines floating down the river, one of which struck a monitor and sank it in deep water.
For nearly six weeks through November, 1914, this deadlock continued. But during all this time, the Austrian General Staff was quietly preparing for another grand drive through Serbia. It was then that the 150,000 reserve, previously mentioned, was assigned to General Potiorek's disposal, while his first line was also materially strengthened.
Nor did the third invasion begin with any dramatic effort. The pressure was applied gradually, little by little, until the Serbs were finally face to face with the necessity of shortening their lines, if they were not to be broken through. Other causes besides the increasing pressure from the Austrians contributed to the general causes.
Winter was coming on in earnest now. The low bottom lands in the Matchva Plain were becoming waterlogged; it was impossible to keep the trenches from filling. The Serbians had, in the first place, made a mistake in attempting to hold these Matchva levels. On such battle grounds, the Magyars, from their own level plains, were too nearly their equals. On level ground, too, the defenders have less the advantage, unless they are in equal number, and the Serbians were everywhere in smaller number. This inferiority, too, made it less possible for the Serbian soldiers to obtain periods of rest away from the constant vigilance necessary in the first line trenches. The result was that they were under a more severe strain. They were subjected to all the drawbacks of trench warfare at its worst, without the respite that is usually accorded to men under these conditions on other fronts. The nerve-racking strain thus imposed became finally more than ordinary human beings could endure. Small wonder that the correspondents with the Serbian army reported many cases of insanity among the men in the trenches.
Finally the order came to withdraw from the Matchva Plain, to the foothills of the Tzer Mountains and the heights along the right bank of the Dobrava River. This retreat, made in the face of no specially strong attack, did not a little to depress the Serbian rank and file. It was beginning to feel that its strength was sapping away.
It was soon obvious that a more general retirement would now become necessary. Complete command of the Tzer Mountains could not be attained without the expenditure of more energy and ammunition than the Serbians could afford at this time. So a general withdrawal was ordered, along the whole line. The Austrians, many of them fresh troops, unused to defeat, followed up in the footsteps of the retreating Serbians with enthusiastic vigor, from Shabatz to Liubovia. And presently Valievo, the railroad terminus and the first objective of the Austrians, became untenable.
On November 11, 1914, the Serbians were compelled to evacuate this city. Its capture was the first step in the progress of the Austrians toward Kragujevatz, Nish and a junction with the Turks near Constantinople. Still, as later events will show, the Serbians were by no means the beaten rabble described by the Vienna press. The score or more of cannon which the Serbians were compelled to abandon on account of the bad condition of the mountain roads were hailed as evidence of a hardly won campaign, and the stragglers captured were accepted as signs of a demoralization which had as yet not set in.
On the other hand, whether this first success was real or not, it did serve to inspire the Austrian troops with an enthusiasm which they had hitherto not possessed.