It was heralded, in fact, at 5 a.m. on the 21st by an intense bombardment in a thick mist which made it impossible for the British batteries to render effective aid to the battered first-line trenches. The onslaught was organized in two parts, the northern advance being directed against Byng's Third Army from the Sensée River to the Cambrai road, and the southern attack from the Flesquières salient opposite Cambrai to St. Quentin. No fewer than 40 German divisions—nearly half a million men—specially
trained for the new offensive, were launched against this southern half, and of these more than half were directed against the 16,500 yards of front held by Gough's Fifth Army nearest St. Quentin. All told, the German drive consisted of 64 divisions on the opening day of the offensive. To meet it the British had but 19 infantry divisions in line and 10 in reserve, with cavalry. From first to last the Germans employed in this attack some 78 divisions—exceeding in numbers the total fighting strength of the whole of the British armies in France. By the 9th of April, when the Germans, foiled in the opening move of their supreme offensive, had shifted the spear-head of their assault to Flanders, the total number of British divisions employed both in cavalry and infantry did not exceed 46.
Some part of the line was bound to give before the terrific impact of the infantry attack which followed the bombardment on 21st March. The plans made for repairing the breach in co-operation with the French broke down for a time because the British Fifth Army, attacked by a far greater force than had been anticipated—23 German divisions having been massed as secretly as possible in order to bring them into position at the critical hour—had been forced back sooner than was expected. There was no time either for the British reserves or the French reinforcements to repair the breach before the assaulting divisions under von Hutier, who had established his reputation for this form of operation on the Eastern front, were through it and extending it in all directions.
There were, in point of fact, two serious breaches along the 42-mile front held by the Fifth Army. One, the less dangerous of the two, was south of the Oise, where the line was held more lightly than elsewhere, owing to the marshes, which had been relied on to make any considerable attack at this point unlikely. As ill luck would have it, a long spell of dry weather had made the ground easily passable, and the Germans, well aware of the position, swept across it in overwhelming force, like a tidal wave. Heroic stands were made for the forward redoubts and battle positions, but the whole of the ground south of the St. Crozat Canal was so submerged in the flood that by nightfall there was nothing for it but to withdraw the divisions of the 3rd Corps, which had been defending it, to the line of the Somme Canal. Nevertheless, though the Germans made their greatest progress on the 21st at this point, it was not their most dangerous thrust, being nearest to French reinforcements.
The chief danger-point was farther north, on the Fifth Army's left, below the Flesquières salient. By noon, with the fog still so thick that it was impossible to see 50 yards ahead, the Germans had advanced as far as Ronssoy, inside the second zone of the British defensive positions, together with Hargicourt and Villeret to the south. This opened a gate to the third line 3 miles wide, and before the day was over the enemy had pushed towards this as far as Templeux-le-Gerard. But for the stubborn defence of Epéhy, to the north, and Le Verguier, to the south, the breach would have been perilously widened on the following day, but at both these points the German advance was temporarily checked. It could not be stayed long. Supplied with an overpowering weight of men to crush through anywhere, von Hutier was ready to pay the price exacted for every success by British artillery-fire at short range, and British machine-gun posts held to the last: and when St. Emilie and Hervilly finally fell on the 21st, Epéhy and Le Verguier could only hold out long enough for the general line of defence to be withdrawn from them. The retreat thence, hard-pressed as it was, left the Fifth Army's centre with a sagging flank to the south, of which the on-coming Germans did not fail to take full advantage. Thenceforward the tide swept on for days in ever-increasing volume, all the reinforcements that Sir Douglas Haig or Pétain could send serving only to stop gaps here and there. Ham, Bapaume, and Péronne had fallen by the 24th, and about two-thirds of the territory wrested from the Germans in 1916 regained by them. Germany was announcing to all the world that the 'Kaiser's Battle', as the emperor himself had caused it to be named, had already been won. To drive the news home, the enemy, on 23rd March, began bombarding Paris with long-range guns capable of firing 70 miles. Nesle and Noyon were the next to go, and by 26th March—save at Albert, which held out until the following day—the Allies were back beyond the line from which they started in 1916.
Elsewhere the enemy's progress along the 60-mile battle front had been slow and costly. He had least success in the north against the British Third Army, partly because the positions held were stronger, partly because his heaviest and most persistent blows had been reserved for the Fifth Army. Some isolated gaps were made on this front, but nothing beyond repair, and the ground lost was not vital. It is impossible in the space at our command to follow all the complications of attack and counter-attack in the fateful days which followed, until, by 26th March, the Germans were within a dozen miles or so of Amiens, with the British Fifth Army still retiring before them in a state of disintegration. At this critical juncture, when the reserves had all been thrown in, General Gough adopted a suggestion made by General
Grant, Chief Engineer of the Fifth Army, that a last line of defence—a forlorn hope to save Amiens—should be formed from stragglers, army school personnel, tunnelling companies, Canadian and American engineers, anyone, in short, who could be roped in. The command of this heterogeneous force, after being organized by General Grant and posted according to General Gough's instructions, was handed over to General Sandeman Carey. 'Carey's force', as it came to be called, aided by the 1st Cavalry Division, which was rushed across the Somme from the north at the same time, earned a special tribute from Mr. Lloyd George in the House of Commons for the magnificent fight which it put up in this last line of defence.
The German effort was becoming spent, though by broadening out the salient the enemy continued to press back the French as well as the British. The French Third Army, sent to the assistance of the British Fifth Army, played a lion's part in preventing him from extending his gains too dangerously in the south. On the 28th he concentrated his main energy against the stubborn British Third Army, which, conforming to the retreating line of the Fifth Army on its right, had fallen back to new battle positions, but in good order. Fresh shock-divisions were brought up to break this northern pivot of the British defence, and, after the usual full-dress bombardment, were launched as before in continual waves of assault. This time, however, there was no fog to handicap the British gunners, who were given the opportunity of a lifetime when they opened fire from hidden positions on serried ranks of German infantrymen, marching shoulder to shoulder at point-blank range. Six times the advance was renewed, and as many times mowed down, and when a final attempt was made, after a second bombardment in the afternoon, it met with similar failure. The Germans had shot their bolt. Their appalling losses on the 28th told on all their subsequent efforts in this first and greatest of Ludendorff's offensives in 1918.