moved into the area that morning and stopped the French advance short of high ground north of Meaux. Overnight, the IV Reserve Corps withdrew to a better position east and French air reconnaissance observed German forces moving north to face the Sixth Army. General Alexander von Kluck the 1st Army commander, ordered the II Corps to move back to the north bank of the Marne, which began a redeployment of all four 1st Army corps to the north bank by 8 September. The swift move to the north bank prevented the Sixth Army from crossing the Ourcq but created a gap between the 1st and 2nd armies. The BEF advanced from crossed the Petit Morin, captured bridges over the Marne and established a bridgehead deep. The Fifth Army also advanced into the gap and by 8 September, had crossed the Petit Morin, which forced Bülow to withdraw the right flank of the 2nd Army. Next day the Fifth Army recrossed the Marne and the German 1st and 2nd armies began to retire as the French Ninth, Fourth and Third Armies fought defensive battles against the 3rd Army which then had to retreat with the 1st and 2nd armies on 9 September. Further east, the Third Army was forced back to the west of Verdun as German attacks were made on the Meuse Heights to the south-east but managed to maintain contact with Verdun and the Fourth Army to the west. German attacks against the Second Army south of Verdun from 5 September, almost forced the French to retreat but on 8 September, the crisis eased. By 10 September, the German armies west of Verdun were retreating towards the Aisne and the Franco-British were following-up, collecting stragglers and equipment. On 12 September, Joffre ordered an outflanking move to the west and an attack northwards by the Third Army, to cut off the German retreat. The pursuit was too slow and by 14 September, the German armies had dug in north of the Aisne and the Allies met trench lines, rather than rearguards. Frontal attacks by the Ninth, Fifth and Sixth armies were repulsed from which led Joffre to begin the transfer of the Second Army west to the left flank of the Sixth Army, the first phase of the operations to outflank the German armies, which from 17 September to moved the opposing armies through Picardy and Flanders, to the North