 The preliminaries began on March 9th, 1918, with millions of high-explosive and gas shells raining across the front between the northern French cities of Pré and Saint-Quentin. The smothering of the British-held territory continued through the week and beyond, and was topped off with a continuous salvo from 6,700 pieces of German artillery, which began at 4.30 in the morning on March 21st.