While we leave the South Africans secure for the moment in the Green Line we must note what happened elsewhere that day on the battle-front. Byng had been the less heavily engaged, and during the day yielded little ground. The enemy’s main effort was against the Fifth Army, especially at the three critical points of the Cologne and Omignon valleys and the Crozat Canal. By midday the canal had been lost, and early in the afternoon Gough was almost everywhere in the third defensive zone. By the evening that zone had been broken around Vaux and Beauvois. Our last reserves had been thrown in, and, save for a French division and some French cavalry, now heavily engaged on the Crozat Canal, there was no help available for the hard-pressed Fifth Army. The gaps could not be stopped, so at all costs our front must withdraw. At 11 p.m. that night Gough gave orders to fall back to the bridgehead position east of the Somme, a position which, as we have seen, was not yet completed. Maxse’s XVIII. Corps was to retire to the river line; Watts’ XIX. Corps and Congreve’s VII. Corps were to hold the Péronne bridgehead on a line running from Voyennes through Monchy-Lagache to Vraignes, and thence continue in the third zone to the junction with the Third Army at Equancourt. This compelled Byng to fall back to conform, and his front ran now in the third zone to Hénin-sur-Cojeul, whence the old battle zone was continued to Fampoux. The third zone was nowhere a real defence, and presently it was clear that the Péronne bridgehead was little better. During the thick night, while the divisions of the Fifth Army, now in the last stages of fatigue, struggled westward, Gough was faced with a momentous decision. He now knew the weight of the German attack; his right flank was in desperate peril; he had no hope of support for several days; and his men strung out on an immense front had been fighting without rest for forty-eight hours. If he faced a general engagement on the morrow he might suffer decisive defeat. There seemed no course open to him but to abandon the Péronne bridgehead, and fall back behind the river. It was a difficult decision, for it shortened our time for defending the river line and for clearing troops and material from the east bank. But the alternative was certain disaster, and beyond doubt in the circumstances Gough’s judgment was right. Accordingly, very early on the morning of Saturday, the 23rd March, instructions were given to Watts to withdraw gradually to the river line, while Congreve, on his left, was to take up a position between Doingt and Nurlu. The front of the VII. Corps would now just cover Péronne on the north, and it would have behind it, flowing from north to south, the little river Tortille. [Sidenote: _March 23._]