On 18 July the army was assigned to the Moscow line of defense occupying positions west of Maloyaroslavets where it was assigned troops. On 25 July the army became part of the reserve commanded by Lieutenant General Ivan Bogdanov, which on 30 July was designated as the Reserve Front the army headquarters located in Lüübnitsa, Russia (now Estonia). On 6 August the army was reassigned to the Northwestern Front.
The army was tasked to defend the eastern bank of the Lovat River from KholmtoKulakovo south of the German-held city of Staraya Russa. STAVKA Directive 00824 tasked the army to strike the left wing of the German forces defeating the forces in the area between Soltsy and Staraya Russa. If successful, the operation could cut off the entire right flank of the Army Group North. According to the order the army was by 15 August to advance more the 25 miles to the line of Snezhka-Chudinovo-Rechnye Kottsy, and by 18 August was to reach the line of Volot-Dolzhino.
By 11 August the army had reached the Polist River along a 24-mile front from Vzglyady to Gojko and launched their offensive. The German X Corps only had small outposts on its flank with the 30th and 129th Infantry Divisions east of Staraya Russa arrayed against the Soviet 11th Army and the 290th Infantry Division on the south side of Staraya Russa guarding the Germ right flank. After the start of the Soviet Offensive the German forces were moved west of Staraya Russa.
The first echelon, consisting of the 245th, 257th, 262nd Rifle and the 25th Cavalry Divisions, advanced quickly reaching there 18 August goals by 14 August and cutting the railroad between Dno and Staraya Russa.
By the end of September the army's line had stabilized to the north and northeast of Demyansk from Lake VellatoLychkovo and remained in these positions through the end of the year.
Prior to the start of the offensive the German successfully withdrew their forces from the Demyansk Pocket and the 34th Army was limited to pursuing rear guard forces. By 28 February the army had arrived at the Lovat River. By the elimination of the pocket the front line had been significantly decreased, and the units of the 34th Army were reassigned to the 11th and 52nd Armies and the headquarters airlifted to the area northeast of Staraya Russa where it took command of some of the forces assigned to the 27th Army.
On 18 March the army, with forces recently reassigned from the 27th attempted to storm Staraya Russa. The army encountered five German divisions along the line of villages Dinner Medvedno, Bryashnaya Gore Sobolev Derevkovo to Porus, the attack was repulsed, restarted on 20 March when it was able to liberate a few small villages moving a little closer to Staraya Russa but unable to liberate the city. The army remained outside Staraya Russa until November 1943 holding the defensive line and attempting to storm the city. On 17–20 August another massive attack was attempted and repulsed again.
On 20 November 1943 the forces assigned to the army were transferred to 1st Shock Army and the headquarters placed in STAVKA reserve. On 15 January 1944 the headquarters was redesignated 4th Army (III formation).
