|Battle of the Vistula River|
|Part of the Eastern Front during World War I|
Eastern Front, September 1914.
|Commanders and leaders|
Paul von Hindenburg|
August von Mackensen
Remus von Woyrsch
Max von Gallwitz
unknown. - 165 000
Second , Fourth , Fifth Army:|
|Casualties and losses|
50,145 KIA, MIA, WIA
|Total 145,309 KIA, MIA, WIA|
By mid-September 1914 the Russians were driving the Austro-Hungarian Army deep into Galicia, threatening Krakow, and the Austro-Hungarian invasion of Serbia was floundering. The armies that the Russian commander Grand Duke Nicholas was assembling in Poland were still enlarging, including the arrival of crack troops from Siberia, freed by the Japanese declaration of war against Germany on 23 August . Stavka (Russian supreme headquarters) intended for the forces assembled south of Warsaw—500,000 men and 2,400 guns—to march west to invade the German industrial area of Upper Silesia, which was almost undefended. On their Eastern Front the Germans had only one army, the Eighth, which was in East Prussia. It already had mauled two Russian armies at Tannenberg and at the First Battle of the Masurian Lakes. To support the reeling Austro-Hungarian Armies, OHL (Oberste Heeresleitung, German supreme headquarters) formed a new German Ninth Army in Silesia, to be commanded by General Richard von Schubert, with Erich Ludendorff, transferred from Eighth army, as chief of staff. Ludendorff quickly evaluated the situation in Silesia and convinced the new commander at OHL, Erich von Falkenhayn, to strengthen the Ninth army and also to make Paul von Hindenburg commander of both German armies in the east. Ninth army, with headquarters in Breslau, consisted of the XVII, XX, XI, Guard Reserve and Landwehr Corps, as well as a mixed Landwehr Division from Silesia and the Saxon 8th Cavalry Division. In early October, the Army was reinforced by the 35th Reserve Division from East Prussia. Thus, Hindenburg had at his disposal 12 Infantry and one cavalry divisions. On 17 September papers from a dead German officer disclosed to the Russians that four German Corps, which they believed to be in East Prussia, were now in Silesia.
To face the threat from Silesia, the Russians withdrew men from East Prussia and from the front facing the Austro-Hungarians The geographical barrier that separated the bulk of the opposing armies was the Vistula River. The Russian corps marching north to fill the gap moved along the east bank of the Vistula, which protected their left flanks. The troop movements involved both the Southwest Front commanded by Nikolay Iudovich Ivanov and the Northwest Front under Nikolai Ruzsky. Their movements were poorly coordinated.
To guard the crossings for their Fourth and Ninth Armies, on the west bank of the Vistula the Russians deployed the 75th Reserve Division (Fourth Army) at Radom, as well as the group of General Delsalle, consisting of the Guard Rifle Brigade, 2nd Rifle Brigade and 80th Reserve Division, at Opatów-Klimontów. Both groups were screened by the Cavalry divisions of the Corps Nowikow. On 28 September German Ninth Army began a meticulously planned advance toward the Vistula River. German XI, Guard and Austro-Hungarian I Corps marched in heavy rain toward Delsalle's group. Because German Army wagons were too heavy for the woeful Polish roads, submerged in several feet of mud, they used light Polish carts hired along with their peasant drivers. As they advanced they improved the roads and bridges so they could support heavy artillery and adjusted the rails to the narrower European gauge. (The Vienna-Warsaw line was already European gauge.) Explosives were cached at road and railway bridges so they could be destroyed if necessary. On 3 October at Klimontów the 3rd and 7th Austrian Cavalry Divisions engaged the Russian Guard cavalry Brigade along with infantry from the 80th Reserve Division and drove them back.
In response to the Austro-German threat, the Russian screen was ordered to fall back. Nowikow's cavalry obeyed, but General Delsalle believed that he could hold his position. The next day, his group was destroyed by the much superior enemy. The Central Powers captured 7,000 prisoners, only a few Russians escaped. The Germans lost 571 men—Austro-Hungarian casualties are not known.
The Germans reached the Vistula River on 9 October. The few Russian bridgeheads on the west bank were invested. Their left flank, August von Mackensen’s XVII Corps, continued to march north until it was 19 km (12 mi) from Warsaw. Only small Russian pockets remained on the west bank; they were excellent targets for the German artillery. General Nikolai Ruzsky, commander of the Russian Northwest Front, sent troops from Warsaw to attack XVII Corps on the German left flank. Orders found on the body of a Russian officer revealed that 14 Russian divisions were concentrating against Mackensen’s 5 divisions. The Germans were also privy to Russian movements from intercepted wireless messages. Unlike the messages sent in the clear during the first weeks of the war, now they were in the new Russian code, which by the end of September had been broken by a German reserve officer, Professor Deubner. Three Russian armies were concentrating against German Ninth Army, relieving the pressure on the Austro-Hungarians in the south. The Germans were impressed by the plan, which they attributed to the Grand Duke, to encircle Ninth Army by the thrust from the north into their rear. To prevent this XVII Corps must be reinforced. The Germans wanted the Austro-Hungarians to provide troops to be hurried to the threatened flank, but the Austro-Hungarians did not want to mingle their men with the Germans, so instead they agreed to take over the line on the German right flank. The released Germans were then moved north, but arrived too late for a prompt, devastating counterattack while the Russians were still concentrating. On 18 October Mackensen withdrew to a defensive line 75 km (47 mi) west of Warsaw.
The Austro-Hungarian First Army, which was taking over the German right flank, was unable to defend the crossings over the Vistula. The Germans claimed that they deliberately allowed the Russians to cross, then intending to engulf them. According to the Austro-Hungarians they arrived too late to prevent the crossings. In any event, the Russians were able to bring enough men quickly over the river to force the Austro-Hungarians to retreat to a line 60 km (37 mi),to the west. According to Max Hoffmann, the third ranking member of Ninth Army Staff, they pulled back without alerting the nearby German units—they escaped only because they were warned by German telephone operator. In fact the Austro-Hungarians did properly inform their allies  In this operation the Austro-Hungarians lost 40,000 men.
On 27 October, Ninth Army was ordered to retreat back into Silesia. The explosive-packed bridges and railways were demolished. By 30 October the battle was over.
The Germans calculated that until extensive repairs were finished the furthest the Russians could advance over the devastated countryside was 120 km (75 mi), so they would have some weeks respite before the Russians could invade Silesia, but they had been forced back. They portrayed the withdrawal as a strategic maneuver, and had succeeded in blocking an enemy advance into Germany for weeks, while their army was trying to win on the Western Front. The retreat "… filled the Russian army with confidence in its strength to deal with Germany". Now Russian troops had beaten both Germans and the Austro-Hungarians. But they dissipated their advantage by indecision about their next move and confusion in their administrative arrangements 
On 1 November Colonel General Hindenburg was given command of all of the German forces in the east while Mackensen took over Ninth Army and Otto von Below led Eighth Army. They returned to the offensive in the Battle of Lodz.
Russian North-Western Front. Commander-in-chief – Nikolai Ruzsky
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