As the British section of the line withdrew, the French, in order to preserve this continuity, were necessarily affected. The French extreme left withdrew behind the Oise to throw this defensive screen before the German attack, gradually extending their left as the British retreat continued, passed Noyons and Pont l'Eveque. As the Allies in their retreat approached the Somme River, the German progress became slower, the efforts were labored. From this point indeed, the huge battle took on something of the nature of the battle of Verdun. It became a fight for limited objectives. Each village offered resistance and became the object of an independent battle. The German advance, however, though slow was not the less persistent and steady. [Sidenote: The Somme divides the field into two areas.] [Sidenote: Montdidier falls.] [Sidenote: French check the Germans at Villers-Bretonneux.] With the crossing of the Somme and the Somme-Aisne Canal on the front between Peronne and Noyons, the battle was automatically divided into two well defined areas by the east and west course of the Somme between Peronne and Amiens. In the southern area, the Allied line was held by both British and French in about equal proportions. But the French were not yet in great force. The Germans, having passed both the Somme and the Canal, fought their way westward step by step, in total disregard of losses, until the line of the Avre River was reached. Here the French, who held the line from the Luce River south and then east, made a position stand, and a series of pitched battles occurred for the river crossing. The first of these to fall was Montdidier at the head waters of the Avre. This enabled the German army to reach westward of the river and spread out after crossing to flank the defenses to the north. Gradually the left bank of the river was cleared as far north as Moreuil. Here the high ground on the left bank between Moreuil and the mouth of the Luce enabled the French to beat off all German attacks for several days. Finally, however, both Moreuil and Morisel were taken and later the village of Cassel, the Avre being thus cleared of the Allied troops as far north as the mouth of the Luce. From Cassel to the Somme, however, the German forces found themselves in serious difficulties. About Hangard, particularly, the fighting was exceptionally heavy; but after changing hands several times, the Germans were finally thrown across to the southern bank of the Luce and there held in place. From Hangard north to the Somme the result was the same. After struggling for days against the troops on the high plateau of which Villers-Bretonneux is the centre, the Germans were brought to a standstill in their attempts to approach Amiens by way of the Avre-Somme angle. [Sidenote: The British retire behind the Ancre.] [Sidenote: Albert is taken; but Germans are soon held.]