If the Germans succeeded in gaining their objective, Sir Douglas Haig's troops separated from their French allies would be penned up in a northwestern corner of France with their backs to the sea, or they would be forced to retreat behind the lower Somme in order to cover their communications with Havre.
The Germans began their great offensive by an intense bombardment of both high explosives and gas shells, while a powerful infantry attack was launched on a front extending from Croisilles to La Fère. The misty weather that prevailed in the morning of March 21, 1918, was favorable for an assault, and the Germans were close to the British lines before they were discovered. In the course of the first onrush they broke through all the British outpost trenches and south of Cambrai penetrated some battle positions.
Forty German divisions were identified by the British as taking part in the first day's attack, but it was believed that at least fifty in all entered the battle before the day closed. At several points the British were heavily outnumbered. Nine German divisions were hurled against three British at one part of the line and eight against two at another.
The German storming troops, including the Guards, made a brave appearance in new uniforms. They advanced in solid ranks until their formation was broken by the intense British machine-gun fire.
Over the dead and wounded the supporting troops swept in countless waves and there was no faltering as the hurricanes of shells swept through their ranks. As hundreds fell others closed in and filled the gaps and the human tide rolled relentlessly on.
The Germans were exceedingly strong in guns. At some points in the line they had one to every twelve or fifteen yards. No less than a thousand confronted three British divisions. With heavy long-range guns they were also well provided and back areas to a distance of twenty-five miles and more were under shell fire.
Among the places against which the Germans first directed their efforts were Bullecourt, Lagnecourt, and Noreuil west of Cambrai, the St. Quentin Ridge on the right of the Cambrai salient, and Ronssoy and Hargicourt south of the Cambrai salient.
The Germans reported that they had captured the British first line between Arras and La Fère and 16,000 prisoners and 200 guns.
On the following day (March 22, 1918,) the fighting reached the greatest intensity in two sectors—one north of Cambrai and the other southwest. The fighting on the northern front was about Bullecourt, while Hargicourt was the southern center. Before attacking the sector between the Canal du Nord and Croisilles the Germans for four hours deluged the British with every kind of projectile and high explosive that a gun could throw.
The British were compelled to fight for hours with their gas masks on, but despite this drawback they were in high spirits because they were able to create such havoc when the Germans advanced in massed formation.