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 6 to 8 September, 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 crossed the Petit Morin, which forced Bülow to withdraw the right flank of the 2nd Army. Next day the Fifth Army re-crossed the Marne and the German 1st and 2nd armies began to retire as the French Ninth, Fourth and Third armies fought defensive battles with the 3rd Army which was forced 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 on 14 September, the German armies 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 on 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 Race to the Sea, reciprocal attempts by the contending armies to outflank their opponent, which from 17 September to moved the opposing armies through Picardy and Flanders to the North Sea coast. Notes Footnotes References Books Journals Further reading Books Reports Websites External links Battle of the Frontiers animation Frontiers 1914 Battle of the Frontiers of France, 20–24 August