The staff-officer must complete by a minute reconnoitring the inspections previously made by the General himself. He should never hesitate to go to the very first lines, and it will be often necessary for him to go under the protection of patrols of infantry, and ascertain in person to what extent the first lines of the enemy have been destroyed, how much damage has been done to the wire entanglements and defences, etc. The staff-officer must be a perfectly trained aërial observer. He should also be competent to detect on the different photographs furnished by the aviators the least damage done to the enemy’s works by the successive projectiles. This task, which must be accomplished most conscientiously, requires excellent eyesight. We do not hesitate to say that, in the present war, it would be criminal insanity to deliver an attack without being sure that the enemy’s wire defences have been sufficiently damaged; at least to such an extent as will allow the infantry to pass through them. A staff-officer should not at this most important juncture trust implicitly to the information furnished him in reports from the first lines or found in the photographs taken by the aviation, but he ought to go and see for himself and report minutely to his Chief. These are dangerous missions: hence the need of having staff-officers in reserve. It has been repeatedly proved that officers who have not been trained at the Ecole d’Etat Major (staff school), but are experienced and efficient men, quickly become excellent substitute staff-officers. Their principal duties may be summed up as follows: Keep their Chief informed before, during, and after an operation. Their office work ought to be limited to the writing of orders and reports concerning the operations. This is easy of accomplishment when the commander has a comprehensive grasp of the situation, and gives his staff clear and concise orders, which they have only to put into effect in due form.