=Aviation.= During the advance, a particular system of liaison is established with the air service. Each division has at its disposal a certain number of accompanying planes that fly low and follow the assaulting battalions. Their duty is to establish communication between the leading elements of the advancing infantry, and the artillery, and the commanding general. The infantry signal to these airplanes by means of rockets and Bengal fires, and the planes in turn communicate with the artillery and the commanding general by means of wireless. CHAPTER VII TRENCH ORDERS The following outline gives a synopsis of information required in various paragraphs for Battalion Orders in Trench Warfare, followed by models of each. Six orders are given in these models, viz.: I. Plan of Attack. II. Order for the Attack. III. Preliminary Order for a Relief. IV. March Order for Relief. V. Plan of Advance. VI. A Raid. I. Plan of Attack (Issued several days before attack) 1. =Rôle of Battalion=, _i. e._, general description of offensive and whether battalion is in first line or reserve. 2. =Zone of Attack.= Accurate description of boundaries of hostile position to be attacked. 3. =Objectives.= Number of trenches to be assaulted and trench at which offensive will halt. 4. =Disposition for the Attack.= Companies in assaulting line—companies in support—apportionment of objectives to companies—distance between assaulting and supporting companies—disposition of M. G. Co. and 37 mm. gun—location of battalion C. O. during assault. 5. =Disposition of Units in Parallels of Departure.= Describe accurately trenches each unit will start from: _e. g._ Assaulting Cos.—first line and cover trenches. Supporting Cos.—intermediate trenches or _places d’armes_ nearby starting points of battalion C. O., M. G. Co. and 37 mm. gun. 6. =Direction of the Attack.= Landmark to guide on, also compass direction. 7. =Tactical Relation with Neighboring Units.= Troops on flanks of battalion and responsibility for liaison therewith. Patrolling to establish connection if necessary. 8. =Artillery Support during Attack.= Barrage to start at hour H. Where and how long it will halt beyond the last objective. 9. =Liaison during Attack.= Usual liaison with artillery and aëroplanes— telephone lines to be established during attack—signals such as Bengal lights to show progress of assaulting companies. 10. =Supply.= Detachments (usually from supporting companies) to carry ammunition. Hour at which and points from which they will start. 11. =Evacuation.= Evacuation point for wounded and assembly point for prisoners. * * * * *