In the last days of August Joffre had to make his great decision. His right was holding before Nancy, and was soon to make a successful advance, clearing most of eastern Lorraine. His center, stretched across the Champagne country from the Argonne to the Oise, had recovered from early reverses and won several considerable local counteroffenses, notably at Guise. But his left was still shaky, his reserves were not yet up and his reconcentration was incomplete. Should he risk all now, or take his army back until his left rested upon Paris? To do this latter would be to surrender more French territory, but it would mean a further exhaustion of the Germans, a further increase in his numbers. The morale of his troops was unshaken. He had suffered defeats, but merely incidental defeats, the real test had not yet come. THE BATTLE OF THE MARNE Joffre decided to continue his retreat, and took his army south of the Marne, his left formed by the British resting upon the forts of Paris, behind which he had massed a new army, his center stretching between Paris and Verdun, his right along the barrier line from Verdun to Switzerland. The German armies, already worn down by their exertions and their losses, were now to be attacked by their foe, whom they regarded as already vanquished. The first phase of the Battle of the Marne was fought northeast of Paris along the Ourcq, which gives its name to the local battle. Kluck had marched past the French capital, going south along its eastern front and leaving only small guards to cover his rear and flank. He had before him the British and on his flank the new Paris army, of the existence of which he was totally ignorant. In Joffre's strategy this army was to strike east while the British struck north, together they were to act like the two blades of a pair of scissors. Between them Kluck was to be destroyed and his rout would expose the flank and rear of all the German forces in France. The French struck with great promptness, but the British failed to move quickly enough. Kluck extricated himself from between the blades with supreme generalship, brought his main force back against the French, borrowing a corps from Buelow and presently the French were driven back upon Paris. British slowness had wrecked the master stroke of Joffre's strategy.