The Riga–Šiauliai offensive (; ) was a major Imperial German Army offensive, launched by Paul von Hindenburg with his Army of the Niemen, to divert Russian forces from the direction of the main German blow of the summer offensive on Narew. However, it gradually changed into an offensive of two German armies to capture the Kaunas Fortress and reach the Daugava. In the course of a successful offensive, the German army defeated the numerically superior Russian forces and reached the approaches of Riga, which was a strategically important city.
Background
Together with the Bug–Narew Offensive of the Max von Gallwitz's Army Group on the Narew and August von Mackensen's Army Group between the Vistula and the Bug Rivers, the Army of the Niemen of the Paul von Hindenburg's army group carried out an operation against the right flank of the Russian Northwestern Front, in fact continuing the active operations begun on the Riga direction at the end of April 1915. This operation was undertaken at the insistence of the Supreme Commander of All German Forces in the East (Ober Ost) - Paul von Hindenburg and his Chief of the Staff Erich Ludendorff, contrary to the negative opinion of Chief of the German Great General Staff, Erich von Falkenhayn. The result of intense disputes was a compromise decision on the distracting nature of the new offensive on the Neman and in Courland, which was more in line with both the more complex natural environment (the area abounded in rivers, forests and swamps), and the importance attached by the Russian command to Riga and the Daugava River. For the Supreme Commander of All German Forces in the East, the main goal of the actions was the envelopment and final capture of the Kaunas Fortress, which supported the Russian battle formations on the Neman - close to the German border.
Comparison of strength
For the offensive on Riga, the Army of the Niemen under Infantry General Otto von Below (Chief of Staff, Major General Alfred von Böckmann) had 158,905 soldiers and officers and 600 guns in service, including only 50 heavy ones, and was operationally subdivided into the strong von Lauenstein's Northern Group and von Richthofen's Southern Group. The first received the task of advancing to the highway from Šiauliai to Jelgava and through Kuldīga to Tukun: the second went on the offensive a few days later, linking the Russian troops along the front.Корольков Г. К. Сражение под Шавли. - М.; Л., 1926, p.8-9
On the Russian side, from the mouth of the Dubysa River to the Baltic coast, the 5th Army of Cavalry General Paul Plehve (chief of staff, Lieutenant General Yevgeny Miller) occupied fortified positions - 217,041 men. Russian troops outnumbered the Germans in manpower and were inferior in artillery (superior in heavy) and, possibly, in machine guns. Experiencing interruptions in the supply of ammunition, like the rest of the Russian armies, the 5th Army was able to dispose of reserves of fortresses and had more opportunities to hold the front.
German offensive on Riga
Russian counteroffensive near Riga
August 2–3 On August 2, the commander of the German 10th Army sent his chief of staff E. Hell to Lötzen to convince the Ober Ost of the need to reinforce the army with at least one division to take Kaunas. Hindenburg promised Hell that the 6th Landwehr Brigade would be transferred from the 8th Army, the Landsturm Regiment and several heavy and super-heavy batteries from the 9th Army, and the Beckman Division would be returned from the Army of the Niemen. The next day, Hindenburg managed to convince Falkenhayn of the importance and possibility of a quick capture of Kaunas; the Supreme High Command allocated the required number of shells for the operation.
On August 2–3, the Army of the Niemen pursued the retreating corps of the Russian 5th Army, capturing 3,250 prisoners and 2 machine guns. After receiving the order to turn the army to Vilnius, O. von Below ordered to stop the pursuit, go on the defensive in the Riga direction, leaving only the 29th Landwehr and the 3rd and 18th Cavalry Brigades here, and send the infantry divisions to the south. To counter the German offensive on Riga, on August 3, Plehve entrusted the defence of the Riga fortified area to Lieutenant General N. Lisovsky, subordinating the 7th Siberian Army Corps to him, and ordered Lieutenant General G. Troubetzkoy to strike at the flank and rear of the Mitava's group.С.Г. Нелипович, 2022, p. 658-659
August 4–7 Due to the retreat of the 19th Army Corps on the night of August 4, Plehve withdrew the 5th Army's other corps. Having received information about the transfer of part of the German troops from Riga, Plehve ordered his troops on August 5 to launch a counteroffensive. In stubborn fighting during the day, the Russians made little progress. The headquarters of the Army of the Niemen regarded the increase in the activity of the Russian side as an attempt to cover the flanks of the army. On August 7, the troops of the Riga fortified area entrenched themselves on the right bank of the Iecava River. In two days, only 40 prisoners were taken.
The offensive of the Army of the Niemen intended to strike at Ukmergė, concentrating three infantry divisions near Panevėžys, but it was necessary to replenish troops and ammunition. At the same time, the chief of staff of the Russian 5th Army, Miller, informed the chief of staff of the armies of the Northwestern Front, A. Gulevich, that with the army sector stretched over 250 versts, “there are absolutely no means to directly cover the paths to Vilnius and Švenčionys". Therefore, he considered the creation of intermediate strongholds unsuitable for the situation and urged that all forces and means be urgently sent to build fortifications in front of Daugava.
August 8–12 After midnight on August 8, Plehve, dissatisfied with the results of the battles, ordered G. Troubetzkoy to personally lead the attack. By the night of August 9, the offensive was a complete success. During the day, more than 50 prisoners and 3 machine guns were captured. On August 9, the 5th Army continued its onslaught on the German center, repelling attempts to advance in the area of the Riga fortified area. In the sectors of the Russian 19th and 3rd Army Corps, the Russian offensive developed successfully. By the morning of August 11, the Army of the Niemen still maintained positions on the Lielupe and Iecava Rivers. Attempts by the Germans to go on the offensive on the front of the Riga fortified area were repulsed by them with the help of gunboats.С.Г. Нелипович, 2022, p. 662
On the afternoon of August 12, in the Riga region, the 13th Siberian Rifle Division launched an offensive towards the Lielupe and knocked out the Germans from the right bank. Plehve, around midnight on August 13, was ordered to Troubetzkoy and M. Grabbe with a concentrated blow to break through the positions of the Germans, and the 3rd and 19th Army Corps to strengthen their positions and conduct active reconnaissance, and in the event of an Germans retreat, vigorously pursue him.Die deutsche kavallerie in Litauen und Kurland, p. 136
August 13–15 On August 13, the Russian 5th Army again attacked the German positions and was met with stubborn resistance and counterattacks. If the 37th Army Corps and the 4th Cavalry Division moved forward and occupied Vecmēmele Manor, then the 1st and 2nd Cavalry Divisions were pushed back beyond the Rovėja river, and the Grabbe's Detachment was not successful. Ordered by Plehve, from 17:00 the 19th and 3rd Army corps went on the offensive. Before nightfall, they managed to get within 300-600 paces of the German positions. The detachment of N. Kaznakov, having suffered significant losses from cannon and machine-gun fire from behind the Šventoji River, retreated. On the night of August 14, Plehve replaced the temporary commander of the 37th Army Corps, Lieutenant General G. Levitsky, with Major General Januarius Tsikhovich, and Troubetzkoy's Detachment was disbanded, leaving only the 1st and 2nd Cavalry Divisions under his command.С.Г. Нелипович, 2022, p. 663
On August 14, the 5th Army resumed the offensive. Until nightfall, the right wing of the army advanced successfully but slowly. The cavalry corps of Troubetzkoy and the detachment of Grabbe were pinned down by the attacks of the German V Cavalry Corps. The offensive of the 19th and 3rd Army Corps developed successfully until noon, but then the German I Cavalry Corps and the 78th Reserve Division launched a counterattack on the left flank of the 3rd Army Corps, after which, at about 17:00, Plehve allowed the corps to withdraw, and ordered the cavalry on the flanks to hit the Germans in the rear. However, the blow did not work, the German I Reserve and I Cavalry Corps continued to push the Russian units, which retreated by the morning of August 15 across the Vadva and rivers.Die deutsche kavallerie in Litauen und Kurland, p. 136
The stubborn battles with varying success that accompanied the offensive of the Russian 5th Army did not bring Plehve the expected results, but the Riga-Daugava direction was reliably covered, the offensive against Ukmergė, which was being prepared by the Germans, was thwarted, and the divisions ready to be sent against Kaunas were detained to hold the positions of the Neman army. The German 10th Army also could not start an operation against Kaunas in time.С.Г. Нелипович, 2022, p. 664
Fall of the Kaunas Fortress
First Vilnius offensive Since mid-August, the staff of Supreme Commander of All German Forces in the East, considered the idea of developing an offensive in the Neman region - by breaking through to Vilnius and Minsk, which would intercept the withdrawal routes of the armies of the Russian Northwestern Front from Congress Poland. For this, as the chief of staff of the Supreme Commander of All German Forces in the East, Ludendorff, believed, it was necessary to break through the Russian positions in front of the 10th Army and Army of the Niemen, push the Russians back through Vilnius to the Daugava and send the cavalry to raid against Minsk and Polotsk to destroy and intercept the railways in the Russian rear. The right flank of the operation was to be provided by the 8th and 12th Armies with an attack on the Pinsk Marshes. Falkenhayn was against such a plan, considering it impossible either to continue the offensive in winter or to invade deep into Russia: operations in the East were not supposed, as emphasised in the order of August 18, to go further than the line from Brest-Litovsk to Grodno, and "surplus" troops were to be transferred to other theaters. Hindenburg disagreed with this vision of military planning: in the area of Augustów and Suwałki, the front passed too close to the German border. On August 19, he issued a new directive: the 12th and 8th Armies to continue attacks. The 10th Army to develop an offensive with the left wing on Vilnius, covering the Russian troops from the Neman to Druskininkai, with the right wing to advance from Augustów to Grodno. The 4th Cavalry Division and three Landwehr divisions from the disbanded X. von Beseler group entered the army. The Army of the Niemen was entrusted with covering the operation from the north with an offensive against Švenčionys and Riga.