Reply fire to hostile shelling. Surprise fire on supply attachments or working parties. Destruction fire on special points. All these fires are called for by telephone, but do not follow automatically like the barrage fire. The artillery commander, in such case, can use a certain amount of discretion whether these fires should be carried out or not. Last of all there is the counter-preparation fire, which is a strong shelling of the enemy’s position. It is carried out as a reply to a methodical bombardment of the enemy preliminary to his offensive. It is the best means to prevent a hostile attack. If this fire is well executed the enemy’s assault is “killed in the egg” as the French expression has it. =Liaison in the Sector.= (_a_) Telephone: There are two different systems of telephones. First, there is the system connecting the infantry command posts, support points, centers of resistance, sector, and division headquarters, with the command posts of the artillery protecting the different infantry areas. These are direct lines between the command posts and the groups of support artillery. Also, this system connects the command post with observatories, depots, medical aid stations, kitchens, etc. Secondly, there is the system connecting the chief of artillery with his subordinate commanders, the artillery observation posts, and the artillery dumps. In this same system the artillery command posts are again connected with the infantry units which they are to support. Special lines are run by the artillery to the officer and N. C. O. of the artillery attachment of liaison in the infantry areas. [Illustration: _Telephone Liaison._] Consequently, the liaison between the artillery and the infantry is doubly provided for in these two systems. The lines of connection between the infantry and the artillery must be separate from those within the infantry area and those between the artillery commander and his subordinate units. Confidential information should never be telephoned except in cipher. Conventional designations are employed to call the different posts. Strict regulations are maintained as to who should use the telephone and for what purposes. The weak point of a telephone system is that it is often broken by bombardment or earth-slides. This can be partially remedied by constructing as few direct lines as possible, by burying the wires in the bottom of the boyaux, and by executing repairs as quickly as possible. (_b_) Wireless and Ground Telegraphy: The battalions in the first line have ground telegraph apparatus connecting them with the regimental headquarters, and these, in turn, can communicate with the general headquarters by wireless. This means of communication is only employed when the telephone cannot be used.