For three hours the Americans and the French fought stubbornly and with every ounce of strength and determination. Whole regiments and even brigades were wiped out on both sides, but the Boches, who had prepared every detail of the assault for weeks, were readier than their opponents and filled the gaps in their lines more quickly. By noon it became apparent that the sacrifice of lives was becoming too great to warrant the Allies trying to hold their first-line trenches much longer, and that they must give them up, at least until they could re-mobilize their forces for a counter-attack. The order was therefore given for those in the rear, including food and ammunition trains, field hospitals, etc., to fall back, in order to make way for the strategic retreat of those on the front when the moment for that retreat came. Everything moved like clockwork, and with the greatest possible speed. And throughout it all men on both sides were shooting, shouting, shrieking, fighting, falling, while others, trapped in their dug-outs, either surrendered or fought desperately on until they fell wounded or lifeless before superior numbers. Half a mile in the air, apparently over a point midway between what had been the first-line trenches of the opposing armies, a stationary balloon showed where Jerry and an observation officer were doing duty on that fateful day. Jerry was operating a telephone that ran directly to division headquarters, and hardly a moment passed when he was not repeating some observation of the other man in the basket with him, or relaying to him a query from the commander below. Every detail of that tremendous battle Jerry knew. His own occasional glimpses over the side informed him of the temporary reverses his own army was suffering, while the remarks of the officer told him where the Germans were meeting their bitterest repulses, where they were drawing up their heaviest forces of reserves, what quick changes were being made in their general line of formation, and how far back their forces seemed to extend. Slim Goodwin, busy as he was with the wireless at headquarters, found time for occasional glances upward at that balloon, to make sure that thus far his friend was still safe. And even in the thick of machine-gun fire and shrapnel, where Lieutenant Mackinson, Joe, Frank Hoskins and two or three others were laying a new line of communication, the wavering, swaying target was watched from time to time, and speculations made as to how long it could remain without being punctured by a bullet, thus forcing its two occupants to resort to their parachutes to make a landing. It was now well into the afternoon. The Germans had swept into the places vacated by the Americans and French, and still the battle raged. It was now that Slim began to wait anxiously for the new development, which his familiarity with the secret orders issued made him know was coming. And finally it did come, and in a way that staggered the Boches.