Moreover, the further and the faster the Germans advanced, the greater became the problem of maintaining their armies. They were advancing into a region without railroads, chewed up by years of warfare, where transportation of food and munitions would be difficult in the extreme. So long as they did not break the Allied line, the further they advanced the worse off they would be. Presently they would put themselves in a position from which they would not be able to extricate themselves except at the risk of defeat. To succeed, the German movement must keep on succeeding. The moment it stopped it was in danger.

Besides, Foch seems to have felt that the great object at this time was to maintain the Allied armies intact until the Americans could arrive in force. At all costs, they must not be beaten before that time. This meant defensive warfare, pursued until it became clear that the Germans could not win. But late in June Foch became convinced that the Germans had failed. They had shot their bolt; they had used up their reserves; and he correctly divined the fact that they had thrust into the battle every man they possessed. They had lost hundreds of thousands during these months of fighting and were now tired and weakened.

Foch knew again that a million Americans had come; millions more were on the way, every week adding to the number in France. They were not, to be sure, experienced troops, only a few of them perhaps were of proper caliber to trust in battle. But they were an admirable reserve. The future was assured: the Americans were on the spot and more Yanks were coming—plenty more. It was possible for him now to throw against the Germans the entire strength of the experienced British and French armies, superb troops, trained by the entire experience of the war. The Americans had made victory possible.

He concluded again that the German advanced positions, won during the great offensive, were only lightly held. There was no long series of trench positions to carry; the Germans had not won this territory to hold it, but merely to use it as a temporary base for a further advance. They ought therefore to be easily driven out of it. If the campaign had been one of movement forward, it might as quickly become one of movement backward, and, once started to the rear, the Germans would probably have to continue the retreat until they reached their old permanent lines. It seemed possible to drive them out of their new gains during 1918, without waiting for further aid from the Americans.

So much was eminently desirable. Paris was in danger; it was being shelled by a long-range German gun and the German armies were all but within sight of it. The effect of victory upon the French and British people would be extraordinary, and if they were to undergo another winter of war it was particularly necessary. Unless they began to have the hope of victory to offset the fears of the spring, it was possible that the Allied morale would weaken. Then there was the submarine. It had by no means won the war. Ship-building in England and America had begun to tell; more ships indeed were beginning to be launched than the submarine was at that time sinking; but it was not wise to put too much confidence in ship-building. The new devices for beating submarines were also effective, but it was better not to rely too much upon them. If the German could be driven back to his old lines before the Americans arrived in force, it was a result peculiarly desirable to achieve.

On July 18, therefore, Foch launched the first of a series of offensives against the west side of the great bulge which the Germans had made in their third assault along the Marne just west of Rheims. The object was to pierce the western side of this salient and thus to force the Germans to retire from its tip or run the risk of being captured. The movement was from the first a glorious success and in it the American troops played a splendid part. They showed such dash, vigor, and skill that the French were electrified. Indeed, their spirit infused into the war-worn French and British a new courage and hope. As the pressure on the western side of this bulge continued, the Germans frantically resisted. Then the French attacked the eastern side of the salient, and the French and Americans began pushing in its center. The German Crown Prince had his troops fairly scrambling over each other trying to escape. The retreat, however, was admirably conducted and the Germans did escape, but by August 7 they had evacuated the entire salient, surrendered all their gains in their third great offensive, and Paris was again safe.

Then Foch struck at the great salients to the north which the Germans had driven into the Allied line in March and April. Pushing here and then there, availing himself with masterly skill of the weakness of the German position, the great general and his assistants so conducted the campaign that by the middle of September the Germans were back again on the old Hindenburg Line. All the gains of 1918 were lost; victory was no longer possible—and the Germans knew it. It was only now a question of the time when the Allies themselves could win the war. Ludendorff declared after the armistice that he had so informed the High Command and the political authorities and had demanded the acceptance of any terms they could secure. But it looked to the great majority in Allied countries in September, 1918, as if the full strength of the Americans would still be necessary to drive the Germans out of their defensive system.