There was a dangerous bulge in the new American line formed by Belleau Wood. In their advance the Americans had been unable to take this forested little stronghold perched on a hill among rocks, and had swept past it, after capturing a near-by elevation, and rushed on to Bouresches. The wood concealed ambushes of German infantry and machine guns, which were a thorn in the side of the Americans on the outskirts. They had made several raids in the wood, expelling groups of Germans here and there; but the next day the enemy would reappear and pour a harassing fire on the American lines. Notwithstanding searching shelling from American guns, the Germans seemed to retain a firm hold. A German attack on June 8, 1918, to oust the Americans from the positions they held on the borders of the wood precipitated an energetic counterassault to clear the enemy completely out. The Americans had already matured plans for riddling the entire woody plateau with a deluge of shells. This artillery scheme was carried out on mathematical lines, the area of the wood being marked off into checkerboard squares, a square to each battery. Every part of the wood therefore had established targets for the American gunners to play upon. The artillery preparation lasted all of Sunday and Monday, June 9 and 10, 1918. It was the most expansive exhibition of ordnance in action that the Americans had undertaken. The wood was raked with more than 5,000 high explosive and gas shells. At 3 o'clock on Monday morning the marines, who had been in conflict with the Germans in their attack of Saturday, proceeded to advance into the wood and penetrated it for two-thirds of a mile on a 66-yard front. The operations were tersely reported by General Pershing to the War Department as follows: "June 11.--Northwest of Château-Thierry we were again successful in advancing our positions in the Belleau Wood. We captured 250 prisoners, of whom three were officers, and considerable material, including a number of machine guns and trench mortars." "June 13--Yesterday afternoon our troops northwest of Château-Thierry captured the last of the German positions in the Belleau Wood, taking fifty prisoners and a number of machine guns and trench mortars, in addition to those taken on the preceding day."