The 'Siauliai Offensive Operation' was a Soviet undertaking by General Hovhannes Kh. Bagramyan’s 1^st Baltic Front within the third phase of the 'Belorussian Strategic Offensive Operation', otherwise known as 'Bagration' 1, to drive the German troops from much of Lithuania and take the city of Siauliai (Schaulen in German) (5 July/20 August 1944).

The German forces involved in this phase of the great Soviet strategic campaign were elements of Generalfeldmarschall Walter Model’s Heeresgruppe 'Mitte' (northern wing of Generaloberst Georg-Hans Reinhardt’s 3^rd Panzerarmee and General Gerhard Matzky’s XXVI Corps) and elements of Generaloberst Johannes Friessner’s Heeresgruppe 'Nord' (southern wing of General Paul Laux’s 16^th Army), while the Soviet forces were those of Bagramyan’s 1^st Baltic Front including General Leytenant Porfiri G. Chanchibadze’s 2^nd Guards Army, General Leytenant Ivan M. Chistyakov’s 6^th Guards Army, General Leytenant Ivan I. Lyudnikov’s 39^th Army, General Leytenant Afanasi P. Beloborodov’s 43^rd Army and General Leytenant Yakov G. Kreizer’s 51^st Army.

During July 1944 'Bagration' had achieved great success, leaving Heeresgruppe 'Mitte' in little more than tatters, and the westward progress made by northern flank of the Soviet assault threatened to trap Heeresgruppe 'Nord' in Latvia and Estonia. The 6^th Guards Army and 43^rd Army involved in 'Bagration' advanced to the line of the Druya river, western Voropaevo and Lake Naroch from 4 July with the task beginning an advance in the direction of Svenčionys, Kaunas and (by other parts of the front) toward Panevezys and Siauliai. Also included in the composition of the front for this operation was the 39^th Army, which was concentrated on the left wing by 10 July. The front was also reinforced with the 2^nd Guards and 51^st Armies from the Stavka reserve, though these could only arrive in the front sector by the second half of July.

The offensive began on 5 July with an assault by two infantry corps of the 6^th Guards Army and three infantry corps of the 43^rd Army, with support from General Major Boris S. Bakharov’s reduced I Tank Corps. Facing them were two German corps, which were positioned on the adjacent southern wing of Heeresgruppe 'Nord' and northern wing of Heeresgruppe 'Mitte'. From the morning of 10 July the 39^th Army was introduced into the battle, advancing in the direction of Kaunas. By 12 July the three armies' assault frontage had increased to some 125 miles (200 km), and Heeresgruppe 'Nord' was still offering stubborn resistance.

As a result of the way in which the offensive was developing, the Stavka now shifted the object of the 1^st Baltic Front’s attack from Kaunas to Siauliai, and the 39^th Army and its sector of its offensive were transferred to General Ivan D. Chernyakhovsky’s 3^rd Belorussian Front on 14 July for the 'Kaunas Offensive Operation'. In exchange the 1^st Baltic Front received General Major Ivan F. Dremov’s III Guards Mechanised Corps. For the development of the offensive on the Siauliai axis, the 2^nd Guards Army and 51^st Army were introduced into the battle on 14 July, and by 22 July had taken Panevezys, an important communications centre for Heeresgruppe 'Nord'. On 27 July the III Guards Mechanised Corps, in co-operation with the combined arms units of the 51^st Army, took Siauliai, which had been held for two days by an extemporised force led by Oberst Hellmuth Mäder, commander of the Lehr-Brigade 'Nord'. The troops of the right wing of the 3^rd Baltic Front collaborated with those of the 2^nd Baltic Front to take Daugavpils (Dvinsk) on 27 July. Pressing home its attack, the 1^st Baltic Front on 30 July overran strongpoints and road junctions near Birzai and Bauska, and by 31 July had reached Jelgava (Mitava). The front’s mobile detachments entered Tukums and reached the coast of the Gulf of Riga just to the south-west of Riga, cutting all German land communications with Heeresgruppe 'Nord'. At the end of July and beginning of August Bagramyan’s forces repulsed German counterattacks in the region of Birzai (some four infantry divisions and as many as 100 tanks and assault guns, according to Soviet estimates) and Raseiniai (one infantry division and one Panzer division).

Between 16 and 29 August the 1^st Baltic Front reported strong counterattacks in the region to the west and north-west of Siauliai (part of 'Doppelkopf'). During these defensive actions, the ground forces were supported by the 3^rd Air Army. By 20 August, by means of counterattacks in the regions to the west of Tukums and Sloki and with gunfire support from warships of the Kriegsmarine, the German forces were able to push the Soviet forces back from the coast in the southern sector and to restore sea communications with their formations around Riga.

The 1^st Baltic Front resumed its offensive during the autumn of 1944, finally destroying much of the 3^rd Panzerarmee and severing the connection between Heeresgruppe 'Mitte' and Heeresgruppe 'Nord' in the 'Memel Offensive Operation'.