On the Eastern Front even following the impressive victories in the East Prussian Campaign, the German position on the Eastern Front was far from secure. Even worse was the total failure of the Austro-Hungarian offensive had stripped them of the ability to launch their own offensive till the spring of 1915 with the Austro-Hungarians use Carpathian Mountains to shield themselves. Worse was the loss of two armies from the Austro-Hungarian TO&E. The Polish Salient had to be dealt with to remove the threat to East Prussia and Berlin itself. It led to the newly formed 9th German Army being assigned to the Eastern Front. This was even with the wildly held belief in the general staff that one good push in the west could knock the French out of the war before they could mobilize the massive colonial resources. They had to remove the eastern threat first.
Russia even through, they were wheeling from their defeat in the East Prussian Campaign they were already plan to counter attack. Instead of East Prussia they were planning to strike into Upper Silesia. At this time, Posen was almost totally undefended and with the area being heavily industrized. They started to mass an army of 500,000 men and 2,000 guns south of Warsaw. However, because of their worry about Germany invading the area the rail network in the Polish Salient wasn’t design to handle this amount of traffic or support their forward positions. This made their slower than what it should had been if the rail network had been built up.
The Russian movements where poorly put together as they move their forces into the Polish Salient to launch their planned offensive into Posen. These movements were found out by German aerial reconnaissance. Germany was one of the biggest believers in military aviation after seeing what the Americans did with it in the Second Mexican American War and had the largest air service at the start of the war with a total of 298 aircraft in service, 100 more than the French and 150 more than the British. With the front in Western Europe running from Switzerland to the Channel the bulk of the German Air Service was moved to the Eastern Front. This allowed the Germans to learn of this pending attack by the Russians.
As this information became known the Germans decided to gamble and allow the Russians to move up to forward positions before attacking them. They weren’t impress by the Russian performance to date and believed that they would make a mistake that would allow them to destroy another Russian Army. The Russians started to move up to forward positions on October 5th. The Germans were keeping tabs on the Russians movements. They waited till October 7th to strike when they launched their assault.
With the Russians on the move they had allowed a gap to form between their 4th and 9th Armies which they were moving up to take part in the planned assault into Posen. The Germans took advance of this gap and launched the 9th Army into it which Russian intelligence had total miss. At the same time the German 8th Army launched an assault to keep the Russian 9th Army tied down and to keep from coming to the aid of the Russian 4th Army. The major problem for the German plan wasn’t the Russians, but the poor if not total lack of infrastructure in the area. Their wagons were having issues staying on the road surface. It wasn’t that they were falling off the roads, it was they were sinking into the roads as the roads couldn’t handle the weight. They had to use local Polish carts as they moved forward and their engineers try to do something with the mess of roads and the railnet in the Polish Salient.
Yet the Russians who were slowly learning from their mistakes in the East Prussian Campaign were still committing too many mistakes this time around. Some were repeats from East Prussia, others through were new mistakes altogether. By the 10th of October the Russian Stavka had sacked both commanders of the 4th and 9th Armies and the front commander for their poor performance in this campaign so far. Yet relieving the 4th Army’s commander was a mistake as the replacement who Stavka had named was already dead having died only that morning only hours before he was named to take over the 4th Army. It left the 4th Army leaderless for 32 hours before a new commander was named. Yet this was all the time needed for the German 9th Army to cut off its final withdraw route.
The Russian 9th Army tried to break a hole in the lines to allowed the trapped Russian 4th Army to escape. Only they were surprised when the Austro-Hungarian 1st Army entered the battle. Even the Germans were surprised when the Austro-Hungarians entered the battle. Yet it caused the Russian 9th Army to break off the assault on the German 9th Army. Working on the fly the Germans and Austro-Hungarians when about encircling the Russian 4th Army. It wasn’t till the 17th of October that the Russian 4th Army surrendered to the joint German and Austro Hungarian forces.
For the 9th Russian Army they abandoned the 4th Russian Army to their fate on the 13th. It also partly because they were worried they would suffer the same fate as the 4th if they didn’t withdraw back to the Warsaw area where the other two armies that had been assigned to the planned invasion of Posen were still at. With their crappy infrastructure, the Russians could only move two armies forward at a time. For the Germans and Austro Hungarians they had forced the Russians back and destroyed another army. That was good enough for now.