While, therefore General Ludendorff with much skill massed die entire German energy in the great salient whose point was on the Oise, the British on the west side and the French on the south side of the salient waited his at tacic in confidence. They did not believe he could break through. They took no effective means to reinforce each other as need should he. Neither general had large reserve forces to re pair a breach if one were made. Each counted on the old methods that had held good at Ypres, the Somme, the Aisne and Verdun, by which it was possible to hold back any assault with only a slight dent in the line of defense.
2. The Offensive of 21 March.—The Ger man blow was expected by the Allies. All through the Iate winter the newspapers had talked about it. As the weather became warm in March and the blow did not fall there was a tendency to decry the danger. Whether it would fall on the British north of the Oise, where the 5th Army under General Gough was in position, or on the French along the Aisne positions it was impossible to say. The Ger mans promoted these doubts by making prepara tions for attack at each pace, and near Ypres as well. Later on they attacked at each of the other places, so that none of the preparations were wasted.
The 5th Army of the British held a front of 41 miles, from the Oise to Gouzeaucourt, 10 miles southwest of Cambrai. It had 11 divi sions in line and five in reserve. North of it, as far as Arras, a front of 23 miles, was the 3d Army under General Byng with 10 divisions in line and five in reserve. These 31 divisions probably contained more than 500,000 men. Most of them became involved in the battle that was about to begin.
The Germans had determined to attack be tween Croisilles and the Oise, a front of 50 miles, which included all of Gough's and nearly two-thirds of Byng's sectors. In their first line in this area they placed 37 •divisions, about 500,000 men, as the German divisions contained about 13,500 men each. They assembled large supports behind the first line and brought them up as needed. -They concentrated efforts at certain points which were critical for hold ing the spaces near them and here they out numbered the British as much as three to one. Two of these important points were near Saint Quentin and one was near Cambrai. The
German High Command took care that the breach to be made was wide enough to permit extensive operations, if the plans went as desired.
The attack was made in the morning of 21 March. A persistent fog hung over the country. At 4:45 an intense bombardment with all kinds of guns was opened. A large number of gas shells were thrown against the British back areas and the gas was held down by the moist air, producing great confusion. High velocity shells fell that day 20 miles behind the front line along most of the area attacked. The men in the trenches suffered frightfully. The fog was so dense that their gunners could not see 50 yards ahead, and no one knew what to shoot at or what to expect. Communication with the rear was impossible except by wireless. In this confusion the men lay in their trenches awaiting attack. It came but not as in previous battles. In one place it came at eight o'clock, at others it arrived later. By 10 the attack was general. The defenders could not see the ap proaching troops until they were actually upon them. Specially selected troops were sent ahead to try out the weak spots in the defense. When a breach was made signals were sent up and other troops were rushed forward to improve the advantage that had been gained. Thus it happened that the line was penetrated at many places while at many others it held firmly. This process of penetration was known as in filtration, and under it the line of defense crumbled until it was reduced to broken bits, each battling for its existence. In many cases the broken remnants held their own, fighting off the German assaults until the last. In other cases they fell back from one place to another as they could, fighting delaying actions. At one o'clock the fog lifted, but two hours earlier the advanced line had been generally taken and the second line was being assailed, heavily in places. All through the afternoon the struggle went on and when night came the Germans had worn the second line thin 10 miles north of Saint Quentin and had made large gains at rhe southern end of Gough's line. During the night the British made some readjustments of their positions and prepared for severe attacics on the following day. Airplanes reported heavy con centrations behind the enemy's lines.