It was strategic withdrawal by Russian forces on the Eastern Front of World War I, after a successful summer German offensive.

Although weakened by the transfer of 12 divisions to France and the Balkans, as part of taking a defense, Hindenburg had his forces conduct several secondary offensive operations.

[4][10] The limited success of the Hindenburg's Army Group after the Siege of Kovno and Siege of Novogeorgievsk forced the Chief of German Great General Staff, General of Infantry Erich von Falkenhayn, to make the final decision to curtail operations in the German Eastern front, especially since large regroupings of troops were necessary for the offensive against Serbia and strengthening the defense in France and Belgium.

On August 27–28, 1915, Emperor Wilhelm II, at the insistence of Falkenhayn, issued a directive on the urgent construction of long-term defensive zones on the Eastern Front from the Baltic Sea in the area north of Mitava to the Narew river further to Kovel.

At the same time, the army groups of Prince Leopold of Bavaria and August von Mackensen should continue the offensive solely with the aim of occupying positions more convenient for defense (bypassing from the north of Białowieża Forest), and the army group of Hindenburg - for "causing a major defeat to the enemy".

As early as August 17, the chief of staff of the Supreme Commander Nikolai Yanushkevich issued a decision on the division of the armies of the North-Western Front despite the objections of the Commander-in-Chief Mikhail Alekseyev.

The position of the armies of the Western Front was complicated by the fact that the Germans stood on the outskirts of Vilno and had already captured Brest-Litovsk.

[5] Parts of the 8th Army managed to overcome the swampy floodplain of the Bobr River in a day and approach the forts of Grodno.

The next day, the Germans managed to capture the intermediate trenches between the forts and cross the Neman River, from the north, parts of the 3rd reserve corps of the German 10th Army, advancing from Druskininkai, cut all roads to Vilno, and the garrison began to leave the forts under the threat of encirclement.

[13] A new transition to the offensive of the armies of the Central Powers, the abandonment of Grodno, the German's exit to the Western Dvina and Lutsk forced Emperor Nicholas II to decide to assume the supreme command.

The cavalry detachment of Lieutenant General Mikael Thylin [ru; fi] was thrown back 10 km from the Širvinta River.

By September 14, the German 1st and 39th reserve corps pushed back the left wing of the Russian 5th army to Dvinsk and captured a bridgehead along a 60-km arc from Lake Salava to Ilūkste: the strike group of the German 10th army advanced to Vileyka and Molodechno, letting in the breakthrough, the cavalry corps of Manfred von Richthofen and O. von Garnier; Sventiany and Naroch were captured, but on the outskirts of Vilno the Germans was repulsed by the forces of the Guards, 3rd Siberian and 5th Caucasian Corps.

The remaining divisions of the cavalry corps of Garnier and Richthofen occupied Zhuprany [ru; be; lt; be-tarask], Baruny, Vileyka and Smarhonʹ with a front to the west and southeast, dedicating a squadron to undermine the Minsk-Smolensk railway (this was only possible on September 20).

[22] On September 17, the 3rd German cavalry division reached the approaches to Molodechno, but 3-4 km from the city was stopped by the arriving units of the Russian 27th Army Corps.

[citation needed] On September 17, the Supreme Commander Nicholas II (and in fact Alekseyev) issued a directive on the withdrawal from the night of September 18 over the next three nights of the armies of the Western Front to the line of Mikhalishki [ru; be-tarask; be; he; lt; pl], Ashmyany, Novogrudok, Baranovichi, Vyhanaščanskaje Lake, and the 2nd Army was given an order to capture Sventiany and Mikhalishki, reestablish contact with the 5th Army of the Northern Front and push back the Germans from Vileyka and Smarhonʹ to Lida and Vilno.

To counteract the enemy cavalry and reach the rear of his grouping on the right flank of the 2nd Army, under the command of Oranovsky, the detachments of Kaznakov, princes K. Toumanov and S. Belosselsky-Belozersky (up to 8 divisions) joined.

[25][26][27] On September 27, Hindenburg stated that the offensive operation was completed and the armies should take a long-term "winter" position from the mouth of the Berezina River to Lake Narach, west of Dinaburg and east of Mitava.

To do this, on September 28, the cavalry group of Oranovsky received the task of breaking through to the rear of the Germans in the direction of Sventiany and pushing the enemy back beyond Panevėžys and Wiłkomierz.

But by this time, to the north of Lake Narach, to the Dvinsk-Jakobstadt road, an army group of artillery general F. von Scholz from the cavalry corps of Richthofen and three infantry divisions was deployed.

[33] The Second offensive on Vilno and the Sventiany breakthrough ended with the advance of the army groups of Hindenburg, Prince Leopold of Bavaria, and Mackensen to the line as a whole outlined by the German Supreme High Command, on which it was necessary to keep the defense in the future.

This was a completely unusual event in military history, when, instead of developing a breakthrough, dozens of divisions were withdrawn from the advancing armies.

The parties' attempts to achieve a turning point in certain sectors of the front before the end of November only led to unjustified losses.