The task was entrusted to the Third Army which had seen little fighting since the battle of Arras died down in the spring, and had been under Sir Julian Byng since Allenby's transference to Egypt. The attack began on 20 November; there was no preliminary bombardment to cut up the ground over which the Tanks, infantry, and cavalry were to advance, and a single gun gave the signal for the start amid a favouring fog and behind a supplementary barrage of smoke which hid the advance from the German guns. The Tanks broke through the wire entanglements and destroyed the nests of machine guns, while the infantry marched forward in their track. By nightfall they had made at points greater progress than on any previous day in the war. Havrincourt, Graincourt, and Anneux--four and a half miles from the morning's front--fell on the left; Ribecourt, Marcoing, Neuf wood, Noyelles, and Masnières in the centre; and La Vacquerie, Bonavis, and Lateau wood on the right. The flies in the ointment of success were a check in front of Flesquières and a serious lack of foresight on the Scheldt canal, where the single bridge was broken at Masnières and the cavalry were held up on a front of several miles. But for the former, Byng might have mastered the vital Bourlon position, and but for the latter have crossed the canal in force, broken the last of the German lines, and taken Rumilly, Crèvecoeur, and possibly Cambrai. For the Germans had been completely surprised and needed two days to bring up any adequate reinforcements. The advance continued at a slower pace on the 21st. Flesquières was taken and then Cantaing and Fontaine-Notre-Dame; but the bid for Bourlon developed into a costly, stubborn, and indecisive struggle for five days while the Germans were being steadily reinforced.