On Sunday the 24th the task of the British was threefold--to stem with French assistance the German advance on our right between the Somme and the Oise, to hold the line of the river from Ham northwards to Péronne, and to repel the German thrust between the Third and Fifth Armies north of the river bend. They were partially successful in the first two tasks, but north of the Somme the Germans got into Combles and the Third Army had to make a big retreat, surrendering Bapaume and nearly all the painful gains of the 1916 Somme campaign. The Germans renewed the attack with great energy on the 25th, and the British were unable to hold them up on their improvised lines. Before night they were ordered to take their stand on the old Ancre defences. This movement exposed the left flank of Gough's forces on the Somme; his front had also been driven in by German attacks across the river, while his right had been forced back beyond Guiscard, Noyon, and Nesle. Fissures began to appear on the broken front; there was something very like a gap between the French and British near Roye, and another between Byng's Fourth and Fifth Corps across the Ancre, besides that between his and Gough's armies. Byng was the first to re-establish his line, partly because reinforcements from the north reached him first. Early on the 26th the Germans had broken through our old line between Beaumont-Hamel and Hébuterne and taken Colincamps, where they had not been since 1914; but in the afternoon they were driven out again, and the recovery was permanent. Here at least the German advance had reached its limit, and there was some significance in the fact that here on that afternoon the British whippet Tanks first appeared in battle. Gough was not so happy. He had begun to collect a miscellaneous force, like that which stopped the final German thrust at Ypres on 31 October 1914, consisting of all sorts of combatant and non-combatant details, to check the German rush on the Somme; but threats on his left, right, and front compelled him to retreat to a line running south from Bray and behind that held by the French before the battle of the Somme. Still the Germans advanced towards Montdidier, seeking to break through between Gough's right and the French, who had been driven off south-west of Roye. But the worst of the danger was north on the Somme, where Byng's orders were misunderstood and his extreme right, instead of holding the line Albert-Bray to protect Gough's left, fell back five miles to Sailly-le-Sec. The result was that on the 27th the Germans were able to cross the Somme behind Gough's left at Chipilly and compel his retreat to a line running from Bouzencourt S.E. to Rosières. There Gough's centre stoutly maintained itself during the day; but to the south the Germans drove the French out of Lassigny and Montdidier and seemed in a fair way to break the liaison between the Allies, while north of the Somme the Germans had got into Albert and Aveluy wood.