The German offensive began during the night of 3 September against the fortifications of the Grand Couronné, either side of Nancy, which pushed back the 2nd Group of Reserve Divisions, comprising the 59th, 68th and 70th Reserve Divisions under General Léon Durand, to the north and the XX Corps of General Balfourier to the south, by the evening of 4 September. In the afternoon of 5 September Castelnau telegraphed to Joffre that he proposed to evacuate Nancy, to preserve the fighting power of the army. Next day Joffre replied that the Second Army was to hold the area east of Nancy if at all possible and only then retire to a line from the Forest of Haye to Saffais, Belchamp and Borville. The civilian authorities in the city had begun preparations for an evacuation but the troops on the Grand Couronné repulsed German attacks on the right flank, during 5 September. The Reserve divisions were only pushed back a short distance on the front to the east and north of Nancy. An attempt by Moltke to withdraw troops from the 6th Army, to join a new 7th Army being formed for operations on the Oise failed when Rupprecht and Dellmensingen were backed by the Emperor who was at the 6th Army headquarters. German attacks continued on 6 September and the XX Corps conducted a counter-attack which gave the defenders a short period to recuperate but the troops of the 2nd Group of Reserve Divisions, east and north of Nancy, began to give way.