to assemble at St. Quentin. Attacks to encircle Verdun from the south and from Soissons to Reims would pin down French troops. On 21 September, Falkenhayn met Bülow and agreed that the 6th Army should concentrate close to Amiens, attack towards the Channel coast and then envelop the French south of the Somme, in a (decisive battle). The XXI Corps, which had moved from Lunéville on 15 September and the I Bavarian Corps which marched from Namur, arrived during 24 September but were diverted against the Second Army as soon as they arrived on 24 September, with orders to extend the front northwards from Chaulnes to Péronne, attack the French bridgehead and drive the French back over the Somme. French offensive preparations French attempts to advance after the German retirement to the Aisne were frustrated after 14 September, when German troops were discovered to have stopped their retirement and dug in on the north bank of the Aisne. Joffre ordered that the German 1st and 2nd armies be attacked but attempts by the Fifth, Ninth and Sixth armies to advance from had little success. French Military Intelligence reported German troop movements from east to west, which led Joffre to continue moving French troops from the east, which had begun on 2 September with IV Corps and continued on 9 September with XX Corps, 11 September with XIII Corps and XIV Corps on 18 September. The depletion of the French forces in the east, took place just before the Battle of Flirey , a German offensive against the Third Army on either side of Verdun, the Fifth Army north of Reims and the Sixth Army along the Aisne, which ended with the creation of the St Mihiel Salient. Joffre maintained the French emphasis on the western flank, after receiving intercepted wireless messages, which showed that the Germans were moving an army to the western flank. Joffre continued to send units to the Second Army, north of the Sixth Army. On 24 September, the Second Army was attacked and found difficulty in holding ground, rather than advancing round the German flank as intended. General Ferdinand Foch ordered the left flank of the French armies to move northward to Arras, Lens and Lille, to recreate a threat to the German northern flank, by moving through Arras to Cambrai and Le Cateau and from Lens to Valenciennes and Maubeuge. If the French occupied the