The Soviet Tallinn Offensive of the 2nd Shock Army commenced in the early morning of 17 September. After the artillery barrage of 132,500 shells and grenades fired at the German II Army Corps, the 8th Estonian Rifle Corps, the 30th Guard Rifle Corps, and the 108th Rifle Corps crossed the Emajõgi in the 25 km wide front segment eastwards from Tartu and went on the offensive with armoured and air support. The defence of the II Army Corps was breached. Only "Rebane" Battle Group placed near Tartu successfully held their front segment. Alfons Rebane extricated his troops with heavy losses. Army Group Narwa and the XXVIII Army Corps, the northernmost elements of Army Group North were at risk of being encircled and destroyed. Schörner ordered Army Group Narwa to abandon the defences of the Emajõgi line and the Narva front to be evacuated from mainland Estonia.