Then north of the great salient just occupied, the Germans struck, on April 9, between the important British depots of Arras and Ypres, forty miles apart, concentrating on a twelve-mile front between Givenchy and Fleurbaix. During the two following days the concentration moved north five miles, penetrating between Armentières and Messines. On the 11th it had developed as far north as Hollebeke, four miles southeast of Ypres, had partly enveloped Messines Ridge and entirely Armentières and the town of Estaires on the Lys River. By the 12th it had swelled beyond Merville and Lestrem in the south, was threatening the railway junction of Bailleul in the middle ground, had gained a footing on Messines Ridge, and was investing the neighboring heights of Neuve Eglise and Kemmel in the north. By the morning of the 17th the German penetration had reached Locon in the south, the Nieppe Forest in the middle ground, and had occupied Bailleul and the eastern heights of the ridge in the north and threatened the western and more elevated heights of Mont Rouge and Mont Kemmel. Thus in eight days the Germans had developed a sector on the Lille front of originally twenty-two miles, a salient embracing an area of about 825 square miles with a new front of about thirty-five miles. SUMMARY OF THE FIGHTING The initial bombardment which preceded the first infantry advance against the Cambrai salient, at 8 o'clock on the morning of March 21, was widely distributed--as far north as Ypres and as far south as the Oise. It consisted mainly of gas and high explosive shells. The first infantry attack, which penetrated the first and second lines on a sixteen-mile front extending from Lagnicourt to Gauche Wood just south of Gouseaucourt, caused a retreat from the salient which had been left exposed to any superior attack since last December. In rapid succession the British positions, now indefinitely exposed on the north, were then attacked between Arras and La Fère, with tremendous concentration between the latter and St. Quentin. According to the German report of the 22d: "After powerful fire by our artillery and mine throwers our infantry stormed in broad sectors and everywhere captured the first enemy line." From the 22d until the 25th the Germans kept up a heavy fire upon the French front, mingled with raids, both land and air, evidently with the intention of preventing a movement of the French behind the lines as long as the German intentions remained uncertain.