flank, the French 17th and 45th divisions attacked near Soissons and gained a foothold on the plateau of Cuffies, just north of the city. The First Battle of Picardy from was the first of the reciprocal outflanking attempts by the French and German armies after the First Battle of the Aisne and resulted in an encounter battle in Picardy. The French Sixth Army attacked up the Oise river valley towards Noyon, as the Second Army assembled further north, ready to advance round the northern flank of the German 1st Army. The Second Army crossed the Avre on a line from Lassigny northwards to Roye and Chaulnes but met the German II Corps from the 1st Army that had arrived from the Aisne front, where new entrenchments had enabled fewer men to garrison the front line. The corps moved into line on on the right flank of the IX Reserve Corps. Despite the assistance of four divisions of the II Cavalry Corps (Lieutenant-General Georg von der Marwitz), the Germans were pushed back to a line from Ribécourt to Lassigny and Roye, which menaced German communications through Ham and St. Quentin. On 21 September, the German XVIII Corps had begun a forced march from Reims and reached Ham on the evening of 23 September. On 24 September, the corps attacked towards Roye and with II Corps, forced back the French IV Corps of the Sixth Army. To the north, the Second Army reached Péronne and formed a bridgehead on the east bank of the Somme, which exhausted the offensive capacity of the Second Army. Joffre sent the XI Corps, the last French reserve, to the Second Army and began to withdraw three more corps for dispatch to the Second Army. On 25 September, a German attack near Noyon pushed back the Second Army. French reinforcements attacked again and from a general action took place along the Western Front from the Vosges to Péronne, after which the main effort of both sides took place further north. Battle 25–29 September The offensive by the French Second Army forced Falkenhayn to divert the XXI and I Bavarian corps as soon as they arrived, to extend the front northwards from Chaulnes to Péronne on 24 September and drive the French back over the Somme. Overcrowded and damaged railways behind the German front slowed the transit of German forces and infantry marched from Namur and Cambrai. On