1. A continuous line of trenches over the whole front, comprising on a limited depth two or three trenches, joined by numerous communicating trenches (_boyaux_), and separated by 100 to 300 metres, each one often protected by a wire entanglement. 2. Centers of resistance, comprising large villages, woods, or immense field works, consisting of a network of trenches which are very strongly organized and in which machine guns under cupolas as well as pieces of artillery are mounted. Such are, for example, the Labyrinth and _Ouvrages Blancs_ of Neuville. These centers of resistance are separated by intervals of 800 to 1,500 metres; they mutually flank each other, and their intervals are generally guarded by closed works. 3. A second line of defense, which is not always continuous. PREPARATION BY THE ARTILLERY. In order to attack with minimum loss, the infantry-requires that the artillery in its preparation carry through the following program: (_a_) _Destroy the wire entanglements._ (_b_) _Neutralize or destroy the defenders of the trenches._ (_c_) _Prevent the artillery from coming into action._ (_d_) _Prevent the bringing up of reserves._ (_e_) _Destroy the machine guns as soon as they reveal their positions._ (_a_) _Destruction of the Wire Entanglement._ The 75 produces sufficient breaches in the wire entanglements for the infantry to get through; in order to accomplish this, each piece remains laid on the same point of the entanglement. But the infantry should not expect the complete and continuous destruction of the entanglement: that would require too many projectiles. (_b_) _Neutralization or Destruction of the Defenders of the Trenches._ The Germans, whenever they can, dig very deep and well protected shelters, in the interior of which they crowd themselves. The 75 has no effect on these shelters, and the infantry of the attack, who are delighted to see the parapets, the sand bags, planks, posts, etc., fly into the air as if pulverized by the ripping detonations, are stupefied on finding themselves greeted by a heavy fire as soon as they start out of their trenches. In consequence of this, the infantry is convinced that whenever the enemy has been able to construct deep shelters, an assault is certain massacre, in spite of the prodigious expenditure of 75’s, unless other and more powerful means of destruction have been employed.