5th. The construction, at the rear of the front of attack, of railroads and ordinary roads in sufficient number, rather in excess of the estimated needs than otherwise; 6th. The organization of the reserves of infantry. 7th. The preparation for the evacuation of the wounded, and the installation of large field hospitals, as close as possible to the lines; 8th. The organization of stations of evacuation; 9th. The organization of the parks; 10th. The organization of the centres of supply, etc. This enumeration, from which we have omitted the aviation, by reason of its special installations on appropriate grounds, gives a sufficient idea of the labour required in preparing an offensive, which takes generally several weeks to accomplish. A few days before the attack, an effort is made to secure the mastery of the air. Destruction fire is then directed against the opposing trenches. The comparison of the different photographic plates handed daily to the General Staffs enables the Command to watch the progress of the destruction of the lines and positions of the enemy. When the destruction is deemed thorough enough, the order is given to attack, at given points, at a given hour of a certain day. The last operation of the artillery, called “the rolling surprise fire,” consists in subjecting numerous portions of the front to a series of terrific and rapid bombardments, which leaves the enemy in doubt as to the points against which the attacks of infantry are to be launched. At the time appointed these attacks commence. The field artillery covers its infantry by barrages as intense as possible. The first assaulting waves, followed by those of the supporting troops, rush to the objectives selected, drive off the enemy by all means at their disposal, occupy and organize them. If necessary, the reserves come in, either to help the assaulting troops, or to repulse the counter-attacks of the enemy, if any occur. [Illustration: Trench “Battemburg” May 4, 1917--Noon] It was decided some time ago that the troops must not, yielding to their ardour, or the excitement of a too easily acquired success, go beyond the objectives that have been assigned to them. A close examination of the defensive dispositions of the Germans which we have described reveals the wisdom of this precaution. It does not follow that additional objectives cannot be taken on the same day, but in this case the additional advance will be made by a fresh attack and the effort will be distributed accordingly. Documents found on Germans in Champagne, in August, furnish the following details of an attack they had prepared north of the Souain Hill. A similar attack had been rendered impossible by the action of the French at Verdun, and by the destruction of the gas reservoirs by the French artillery.