During the last battles on the Somme, on the Aisne, and at Verdun, advanced infantry fractions had to hold out for several days in shell-craters, not connected with one another, and often filled with water. The heavy enemy shell-fire rendered every move impossible and stopped the arrival of all supplies. The adverse lines were often merged into one another and from hole to hole grenade fighting was kept up. It was nevertheless under such trying conditions that our troops fought inch by inch to defend the French lines at Verdun, and their heroic resistance enabled the Command to prepare new positions, to redistribute the troops and to move them forward, after they had finally thwarted the great German effort. [Illustration: View taken about 10 A.M. during the attack of May 5, 1917] POSTS OF COMMAND. In a division all the commanders of units from the General of Division to the Major direct the fight from quarters called Command Posts. These quarters, rendered as much as possible proof to field artillery fire, must overlook the battlefield. They are fitted with all the rapid means of communication, both telegraph and telephone. The wires, although numerous and deeply buried seldom resist the bombardment until the time of attack. As a last resource recourse is had to signals, optical devices, carrier-pigeons, and messengers. Apparatus for ground-telegraphy, which seems destined to come into general use, has lately been employed, but we have not seen it in operation. As communications between the advanced lines and the rear have become so very difficult during the preparation bombardment and the barrages, which are often uninterruptedly kept up for several days, the western armies have again had recourse to the carrier-pigeons, which are furnished in large numbers by private societies, existing before the war. Their co-operation is very useful and helps to save many human lives. They are also sent out by airplanes whenever the use of wireless telegraphy is not deemed expedient. They render great service in keeping the front in communication with the rear, and are also of priceless value for connecting the rear with the front. SIGNALLING. The difficulty of communication between the rear and the front during the bombardments will necessitate the increasing use of infantry aircraft for the direction of operations. The aircraft, connected by wireless with the various divisional headquarters, are able to send information and in turn, to receive and transmit orders by signal to the troops on the front. These aircraft will also maintain a connection between the infantry and the field artillery, which must be close and continuous if demoralizing consequences, such as have only too frequently occurred in all camps, are to be averted.