Sea coast. First Battle of the Aisne, 13–28 September On 10 September, the French armies and the BEF advanced to exploit the victory of the Marne and the armies on the left flank advanced, opposed only by rearguards. On Joffre ordered outflanking manoeuvres but the advance was too slow to catch the Germans, who on 14 September, began to dig in on high ground on the north bank of the Aisne, which reduced the French advance from to a few local gains. French troops had begun to move westwards on 2 September, over undamaged railways which could move a corps to the left flank in from On 17 September, the French Sixth Army attacked from Soissons to Noyon, with the XIII and IV corps, supported by the 61st and 62nd divisions of the 6th Group of Reserve Divisions, after which the fighting moved north to Lassigny and the French dug in around Nampcel. The French Second Army arrived from the eastern flank and took over command of the left-hand corps of the Sixth Army, as indications appeared that German troops were also being moved from the eastern flank. The German IX Reserve Corps arrived from Belgium by 15 September and next day attacked with the 1st Army to the south-west with the IV Corps and the 4th and 7th cavalry divisions, against the attempted French envelopment. The attack was cancelled and the corps withdrew behind the right flank of the 1st Army. The 2nd and 9th cavalry divisions were sent next day but the French attack reached Carlepont and Noyon, before being contained on 18 September. In the Battle of Flirey, the German armies attacked from Verdun west to Reims and the Aisne on 20 September, cut the main railway from Verdun to Paris and created the St Mihiel salient. The main German effort remained on the western flank, which the French discovered by intercepting wireless messages. By 28 September, the Aisne front had stabilised and the BEF began to withdraw on the night of with the first troops arriving in the Abbeville area on Prelude German plan of attack After the defeat on the Marne, Moltke ordered a retirement to the Aisne by the 1st and 2nd armies on the German right wing and a withdrawal to Reims and a line eastwards past the north of Verdun, by the 3rd, 4th and 5th armies. The 6th and 7th armies