Any officer of the sector, as for example a machine gun officer, has access to this file to more thoroughly acquaint himself for the execution of his duties. CHAPTER V DEFENSE OF A POSITION Different Kinds of Hostile Attacks =Surprise Attacks.= These may be raids or local attacks. A raid is usually for the purpose of taking prisoners; and a local attack, to capture a part of the line. These operations may be carried out without a preliminary bombardment, but are usually preceded by a short intense bombardment to destroy wire entanglements. =Attacks in Force.= Such an attack may be made on a larger part of the line, as a particular sector, or on a considerable length of front in a general offensive. This kind of attack is, of course, preceded by a bombardment. =Special Attacks.= Special attacks are made with gas, liquid fire, and mine methods. These will be taken up in detail in a later chapter. Surprise Attacks =Precautions Against Surprise.= In considering precautions against surprise attacks, it is not a question of combating patrols or enemy’s reconnaissance parties whose missions are to search out information of your intentions and situation. It is a question of raids and little attacks on your lines. Against such hostile operations the defense of the sector depends upon the following precautions. =Maintenance of the Barbed Wire Entanglements.= A surprise attack, to be successful, must have besides surprise the element of swiftness. The enemy must make a dash across “No Man’s Land” up to your first line. This, however, is impossible, if your barbed wire entanglements are intact. Consequently each captain is responsible for the maintenance of the wire belt in front of his line. It is the duty of the observation service to discover breaches or defects in your wire. To this end, the captain sends out at night patrols to ascertain the condition of his entanglements. If necessary, small detachments are sent out at night to make repairs. If this work is considerable, he calls upon the battalion commander for special working parties to assist. The captain, in his daily requisitions for material, provides for the supply of wire, chevaux-de-frise, etc., that he may need. =Service of Guard and Observation.= One of the most important duties of the observers in the first line, and of the sentinels and patrols, is to locate breaches that the enemy has made in your wire, or to discover hostile parties in the act of tampering with the same. Breaches or passages in your wire may be made by such means as bangalores and petards and detonators. The explosion of such an arrangement is a sufficient signal of alarm. These are usually poor methods.