An hour later, at 0100 hours, the opening bombardment of "Blücher-Yorck" began, augmented with poison gas and described as 'of a violence and accuracy that in the opinion of the most seasoned soldiers far outdid any other barrage they were under'. Sheltered as they were in dugouts deep underground, the Devons' casualties were light, although the gas caused some discomfort and inconvenience, and ammunition parties could not be sent out. At approximately 0345, the German infantry attack began using the recently developed Stormtroop tactic of advancing rapidly, probing for weak spots and avoiding pockets of resistance. The units in the front-line trenches, which had already suffered severely from the artillery bombardment, were rapidly infiltrated and overrun. Soon the 8th Division's only cohesive unit of any size north of the River Aisne was the 2nd Devonshires.