On Aug. 30 the German plan of strategy was changed, and it was resolved to break the centre of the enemy, throwing his left wing into Paris and on the Seine and his right wing into Verdun, Toul, and Epinal. The armies of the centre were pushed forward, while either wing held back. The Allies were established in the general line Paris-Verdun. The battle ensuing on Sept. 5 and the retreat of the Germans to the Aisne are the events of the third period of this campaign, lasting from Sept. 5 to Sept. 28. On Sept. 8, while the German attacks had all but pierced the French centre, having already bent it back beyond the line Sezanne-Vitry, the German right wing found itself outflanked by a new allied army from Paris, which was rapidly moving northward and threatened to roll up the entire German battle front from the direction of Compiegne. The critical question, who would succeed first, the Allies in outflanking the German right or the Germans in piercing the French centre, was decided in favor of the Allies. Anglo-French strategy triumphed. The tactical aspect of the situation, though, is best illustrated by the message sent to his commander-in-chief by General Foch, commanding the French Army of the Centre when he received the order to counter-attack: "My left has been forced back, my right is routed. I shall attack with the centre." When the counter-attack came it found but rear guards opposing it. The retreat of the Germans, their right flank constantly in danger of being rolled up, was a fine military achievement. On Sept. 12 it halted on the Aisne. In the regions northeast of Verdun the German left wing joined hands with the Sixth German Army, which had followed up the retirement of the French Army of Lorraine to the line Verdun-St. Die. Thus resting on Metz with its left wing the German battle-front was strongly established on a line passing Verdun, to the east and northeast, extending from there in a general westerly direction to the valley of the Aisne as far as the region north of Compiegne, and from that point northward to the region west of Peronne and Cambrai. The stability of this line, enabling a constant shifting of forces toward the right wing, and the arrival there of the army released from Maubeuge, made possible the extension of the battle-front to the region of Arras, and frustrated all flanking movements on the part of the Allies. The situation was again safe, but the plan to put the French army hors de combat was far from having been realized. The German General Staff therefore decided on a new plan. Its purpose was to gain control of the northeast coast of France. A wedge should be driven between the two allied countries, and Pas-de-Calais made the base of further operations against both. The following out of this plan constitutes the fourth and last period of the first phase of the western campaign. It starts with the beginning of the siege of Antwerp on Sept. 28 and ends with the first battle of Ypres on Oct. 27.