In July 1944, The Soviet Operation Bagration had been achieving great success. Army Group Centre was in tatters, and the northern edge of the Soviet assault threatened to trap Army Group North in Latvia and Estonia. Front forces (the 6th Guards and 43rd Armies), participating in the Belorussian strategic offensive operation, advanced to the line of the Druya river, west of Voropaevo and Naroch Lake from 4 July, having the mission of beginning an advance in the direction of Švenčionys, Kaunas and by part of the forces towards Panevėžys and Šiauliai. Also included in the composition of the Front for this operation was the 39th Army, which had to be concentrated on the left wing of the Front by 10 July. The Front was also reinforced by the 2nd Guards and 51st 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 the forces of two rifle corps of the 6th Guards and three rifle corps of 43rd Armies, with support from a reduced 1st Tank Corps.