Beyond the first German line, which was just south of Grand Boureuilles and Petite Boureuilles, on opposite sides of the Aire river, the German defenses had not been so thoroughly destroyed and the resistance began to stiffen. Out from their shelters, as soon as the American barrage had passed them, came hordes of Germans to man their concealed machine gun nests. The lessons of the Marne-Aisne drive had been well learned by the Pennsylvanians, and there were few frontal assaults on these strong points, many of which were the famous concrete "pill boxes"--holes in the earth roofed over with rounded concrete and concealed by foliage and branches, with narrow slits a few inches above the surface of the earth to permit the guns to be sighted and fired. When the infantry came to one of these that spat flame and steel in such volume that a direct attack threatened to be extremely costly, they passed around it through the woods on either flank and left it to be handled by the forces coming up immediately in their rear, with trench mortars and one-pounder cannon, capable of demolishing the concrete structures. The infantry passed beyond the area in which the artillery and trench mortars had wiped out the barbed wire and ran into much difficulty with the astounding network of this defensive material woven through the trees. The Germans had boasted that the Argonne forest was a wooded fortress that never could be taken. American troops proved the vanity of that boast, but they went through an inferno to do it. The wire was a maze, laced through the forest from tree to tree, so that hours were consumed in covering ground which, but for the wire, could have been covered in almost as many minutes. The men had literally to cut and hack their way through yard after yard. The towns of Boureuilles, great and small, were cleaned up after smart fighting, and the advance was continued up the beautiful Aire River valley in the direction of Varennes. The Pennsylvania infantry was advancing in two columns. The 55th Brigade, including the 109th and 110th Infantry regiments, was right along the river, and the 56th Brigade, made up of the 111th and 112th, went through the forest on the left, or west of the river. On the right of the Twenty-eighth Division was the Thirtieth Division, consisting of National Guard troops of North and South Carolina and Tennessee, and on the left was the Seventy-seventh Division, selected men from New York State. The town of Varennes stands in a bowl-shaped valley, rich in historic significance and, at the time our men reached there, gorgeous in the autumnal colorings of the trees. It was at Varennes that Louis XVI was captured when he attempted to escape from France.