The doughboys knew that something big was impending. They had come to believe that "Pershing wouldn't have the Twenty-eighth Division around unless he was going to pull off something big." They felt more at home than they had since leaving America. All about them they saw nothing but American soldiers, and thousands upon thousands of them. The country seemed teeming with them. Every branch of the service was in American hands, the first time the Pennsylvanians had seen such an organization of their very own--the first time anybody ever did, in fact, for it was the biggest American army ever assembled. Infantry, artillery, engineers, the supply services, tanks, the air service, medical service, the high command and the staff, all were American. It was a proud day for the doughboys when showers of leaflets dropped from a squadron of airplanes flying over one day and they read on the printed pages a pledge from American airmen to co-operate with the American fighting men on the ground to the limit of their ability and asked similar co-operation from the foot soldiers. "Your signals enable us to take the news of your location to the rear," read the communication, "to report if the attack is successful, to call for help if needed, to enable the artillery to put their shells over your heads into the enemy. If you are out of ammunition and tell us, we will report and have it sent up. If you are surrounded, we will deliver the ammunition by airplane. We do not hike through the mud with you, but there are discomforts in our work as bad as mud, but we won't let rain, storms, Archies (anti-aircraft guns) nor Boche planes prevent our getting there with the goods. Use us to the limit. After reading this, hand it to your buddie and remember to show your signals." It was signed: "Your Aviators." "You bet we will, all of that," was the heartfelt comment of the soldiers. Such was the splendid spirit of co-operation built up by General Pershing among the branches of the service. To this great American army was assigned the tremendous task of striking at the enemy's vitals, striking where it was known he would defend himself most passionately. The German defensive lines converged toward a point in the east like the ribs of a fan, drawing close to protect the Mezieres-Longuyon railroad shuttle, which was the vital artery of Germany in occupied territory. If the Americans could force a break through in the Argonne, the whole tottering German machine in France would crumble. Whether they broke through or not, the smallest possible result of an advance there would be the narrowing of the bottle-neck of the German transport lines into Germany and a slow strangling of the invading forces.