to transfix the men who caught in the trip wire and fell.
Behind the wire tangle were the enemy first line trenches.
These were immense works, designed as permanent field fortresses. They were always well made and well sited. In many important points of the line they were twelve feet deep, and strongly revetted with plank and wicker. At intervals of about 50 yards, in some parts of the line, were little concrete forts for observers and machine guns. These forts were so well concealed that they could not be seen from without. The slit for the observer or for the machine gun to fire through is very tiny, and well hidden in the mud of the trench parapet.
These forts were immensely strong, and very small. A man inside one could only be destroyed by the direct hit of a big shell or by the lucky chance of a bullet coming through the narrow slit. You must remember that one cool soldier with a machine gun has in his hands the concentrated destructive power of 40 or 50 rifle men.
In the wall of the trench parapets on this front line, at intervals of 30 to 40 yards, were