In order to meet the difficulty of securing tonnage for supplies and to avoid competition with the Allies, a General Purchasing Board was created for the coördination of all purchases. Agents of this board were stationed in the Allied countries, in Switzerland, Holland, and Spain, who reconnoitered resources, analyzed requirements, issued forecasts of supplies, supervised the claims of foreign governments on American raw materials, and procured civilian manual labor. Following the establishment of the supreme interallied command, the Interallied Board of Supplies was organized in the summer of 1918, with the American purchasing agent as a member. Other activities of the S. O. S., too numerous to recount in detail, included such important tasks as the reclassification of personnel, the installation and operation of a general service of telephone and telegraph communication, with 115,500 kilometers of lines, and the renting and requisitioning of the land and buildings needed by the armies. It was a gigantic business undertaking, organized at top speed, involving tremendous expenditure. Its success would have been impossible without the coöperation of hundreds of men of business, who found in it a sphere of service which enabled the army to utilize the proverbial American genius for meeting large problems of economic organization. At the time of the armistice the S. O. S. reached a numerical strength in personnel of 668,000, including 23,000 civilian employees.

From the first, Pershing had been determined that the American Expeditionary Force should ultimately operate as an independent unit, although in close coöperation with the Allies. During the autumn of 1917 the disasters in Italy and the military demoralization of Russia had led to the formation of the Supreme Military Council of the Allies, upon which the United States was represented by General Tasker Bliss, whose rough visage and gruff manner gave little indication of his wide interests. Few suspected that this soldierly character took secret pleasure in the reading of Latin poets. The coördination that resulted from the creation of the Supreme Council, however, proved insufficient to meet the crisis of the spring of 1918.

On the 21st of March, the Germans attacked in overwhelming force the southern extremity of the British lines, near where they joined the French, and disastrously defeated General Gough's army. The break-through was clean and the advance made by the endless waves of German shock-troops appalling. Within eight days the enemy had swept forward to a depth of fifty-six kilometers, threatening the capture of Amiens and the separation of the French and British. As the initial momentum of the onslaught was lost, the Allied line was re-formed with the help of French reserves under Fayolle. But the Allies had been and still were close to disaster. Complete unity of command was essential. It was plain also, in the words of Pershing's report, that because of the inroads made upon British and French reserves, "defeat stared them in the face unless the new American troops should prove more immediately available than even the most optimistic had dared to hope." The first necessity was satisfied early in April. The extremity of the danger reinforced the demand long made by the French, and supported by President Wilson through Colonel House, that a generalissimo be appointed. The British finally sank their objection, and on the 28th of March it was agreed that General Ferdinand Foch should be made commander-in-chief of all the Allied armies with the powers necessary for the strategic direction of all military operations. The decision was ratified on the 3d and approved by President Wilson on the 16th of April.

General Foch had long been recognized as an eminent student of strategy, and he had proved his practical capacity in 1914 and later. It was he who commanded the French army that broke the German line at the marshes of St. Gond, in the battle of the Marne, thus assuring victory to Joffre, and he had later in the year secured fresh laurels in the first battle of the Yser. At the moment of extreme danger to Italy, after Caporetto, in 1917, he had been chosen to command the assisting force sent down by the French. Unsentimental and unswayed by political factors, he was temperamentally and intellectually the ideal man for the post of supreme Allied commander; he was furthermore supported by the capacity of General Pétain, the French commander-in-chief, and by a remarkable group of army commanders, among whom Fayolle, Mangin, and Gouraud were to win particular fame. But he lacked troops, the Germans disposing of 200 divisions as against 162 Allied divisions.

Hence the hurry call sent to America and hence the heavy sacrifice now forced upon Pershing. Much against his will and only as a result of extreme pressure, the American commander-in-chief agreed to a temporary continuance of the brigading of American troops with the British and the French. He had felt all along that "there was every reason why we could not allow them to be scattered among our Allies, even by divisions, much less as replacements, except by pressure of pure necessity." He disliked the emphasis placed by the Allies upon training for trench warfare; he feared the effect of the lack of homogeneity which would render the mixed divisions "difficult to maneuver and almost certain to break up under the stress of defeat," and he believed that the creation of independent American armies "would be a severe blow to German morale." When the pinch of necessity came, however, Pershing sank his objections to amalgamation and, to his credit, agreed with a beau geste and fine phrase which concealed the differences between the Allied chiefs and won the heartiest sympathy from France and England. The principle of an independent American force, however, Pershing insisted upon, and he made clear that the amalgamation of our troops with the French and British was merely a temporary expedient.

Immediately after the stabilization of the battle-line near Amiens, the Germans began their second great drive, this time against the British along the Lys, in Flanders. The initial success of the attack, which began on the 9th of April, was undeniable, and Sir Douglas Haig himself admitted the danger of the moment: "Every position must be held to the last man. There must be no retirement. With our backs to the wall and believing in the justice of our cause, each one of us must fight to the end. The safety of our homes and the freedom of mankind depend alike upon the conduct of each one of us at this critical moment." The value of Allied unity of command now became apparent, for heavy French reinforcements were brought up in time to help stave off the German drive on the Channel Ports.

But still the demand went up for more men and ships. "Scrap before shipping every pound that takes tonnage and is not necessary to the killing of Germans," wrote a French military authority. "Send the most infantry by the shortest route to the hottest corner. No matter what flag they fight under, so long as it is an Allied flag." On the 27th of May the Germans caught Foch by surprise and launched a violent attack on the Chemin des Dames, between Soissons and Berry-au-Bac. This formed the third phase of their great offensive. In four days they pushed before them the tired French divisions, sent into that sector to recuperate, a distance of fifty kilometers and reached the Marne. Again, as in 1914, Paris began to empty, fearful of capture. A statement sent to Wilson on the 2d of June and signed by Clemenceau, Lloyd George, and Orlando, read as follows: "There is great danger of the war being lost unless the numerical inferiority of the Allies can be remedied as rapidly as possible by the advent of American troops.... We are satisfied that General Foch ... is not over-estimating the needs of the case." Such was the peril of the Allies. But in the month of May 245,000 Americans had been landed, and in the following month there were to be 278,000 more.

Previous to June, 1918, the participation of American troops in military operations had been of comparative unimportance and less for tactical purposes than as a part of their training. In October, 1917, the First Division had been sent into trenches on the quiet Lorraine front and had engaged in raids and counter-raids. Three other divisions, the Second, the Forty-second, or "Rainbow," and the Twenty-sixth from New England, followed, and by March, 1918, they were all described by Pershing as "equal to any demands of battle action." On the 29th of April, the last-named division was engaged in something more serious than a mere raid at Seicheprey, near St. Mihiel; the number of prisoners lost indicated lack of experience, but the vigor of the American counter-attack proved definitely the will to fight. That belligerent spirit was equally displayed by various engineering units which, during the break of General Gough's army before the German assault of March, near St. Quentin, had dropped their tools, seized rifles, and, hastily organizing to cover the retreat, had secured valuable respite for various fleeing units.

More important yet, because of the moral effect achieved, was the engagement at Cantigny near Montdidier, on the 28th of May. The Americans launched their attack with skill as well as dash, and stood firm against the violence of the German reaction; this they met without assistance from the French, who had been called to oppose the German advance on the Marne. Pershing spoke of the "desperate efforts" of the enemy at Cantigny, "determined at all costs to counteract the most excellent effect the American success had produced." For three days guns of all calibers were vainly concentrated upon the new positions. Coming at the moment of extreme discouragement, Cantigny was of an importance entirely out of proportion to the numbers involved. For months France had been awaiting American assistance. A year before the French had seen Pershing and the first few doughboys, but the long delay had caused them to lose the confidence which that sight had aroused. Now suddenly came the news that the Americans were arriving in tremendous numbers and from Cantigny, north and south along the lines, spread the report: "These men will fight."

Four days later at Château-Thierry,[11] Americans proved not merely the moral but the practical value of their assistance. The German drive of the 27th of May, beginning on the Chemin des Dames, had pushed south to the Marne and westward towards Meaux. The French falling back in haste had maintained their lines intact, but were pessimistic as to the possibility of stopping the enemy advance. On the 31st of May, German vanguard units entered Château-Thierry, crossed the river, and planned to secure the bridges. At this moment American machine gunners of the Third Division came up with a battalion of French colonials in support, drove the Germans back to the north bank, covered the retreat of the French forces across the Marne, on the following day, and gave time to blow up the bridges. On the same day, the 1st of June, northwest of Château-Thierry, the Second Division came into line to support the wearied French, and as the latter came filtering back and through, soon found itself meeting direct German assaults. Stretching across the road to Paris, with the French too weak to make a stand, it blocked the German advance. Even so, the danger was not entirely parried, since the enemy held strong positions from Vaux northwest to Veuilly, which, when German reinforcements came up, would enable them to deliver deadly assaults. Those positions had to be taken. From the 6th to the 11th of June, American troops, among them marine regiments, struck viciously, concentrating against the railroad embankment at Bouresches and the hill of Belleau Woods. The stiffness of the German defense, maintained by their best troops, was overcome by fearless rushing of machine-gun nests, ruthless mopping-up of isolated stragglers, and a final clearing of the Woods by heavy artillery fire. On the 18th of June the Americans took the approaches to Torcy and on the 1st of July the village of Vaux. If the attack on Belleau Woods proved their courage, the capture of Vaux vindicated their skill, for losses were negligible.