Reconnaissance during battle has been dealt with under "Influences on the Battle" and in other lectures, and owing to the close connection between the two subjects a number of points concerning reconnaissance in general have been noted in dealing with Protection. It has also been seen that observation by Aircraft, Patrols, and Sentries is essential to Protection both in Position Warfare and the War of Manoeuvre, and that Reconnaissance is the essence of Protection. There remain, however, two forms of Reconnaissance that have not yet been considered, namely: the Reconnaissance of a Position with a view to attacking it, and the Reconnaissance of an unoccupied position with a view to occupying it for defence. RECONNAISSANCE FOR ATTACK.--The first of these is the constant duty of all commanders in the line during Position Warfare, and it is carried out by Patrols and Raiding Parties, who provide information which supplements the photographs and reports of the Air Service, and enables a commander to arrive at a decision. In a War of Manoeuvre reconnaissance by the Air Service is equally important, and it is supplemented by the work of the Patrols of the Advanced Guard, but principally by that of specially selected Intelligence Officers, working in conjunction with, or independent of, the Vanguard. Such officers would be in possession of information which it might not be possible to reveal to the commander of the Patrols of the Vanguard, and their special training would give an added value to their report. The chief {142} points to be ascertained concerning a hostile position are:-- I. The extent of the position occupied. II. Weak points of the position. III. Points, the capture of which would facilitate enfilade or reverse fire, and would thus render the rest of the position untenable. IV. Best line of attack. V. Supporting positions, for covering, converging, enfilade, and traversing fire. It should be possible to gather this information without alarming the enemy, or giving notice of impending attack. Information on further points can be gained by fighting, and _Reconnaissance by Raids_ is a common feature of Position Warfare. By such means additional information can be gained, as to:-- VI. Names of regiments holding the position, judged from identity discs, badges, buttons, etc. VII. Whether preparations are being made for an attack (discoverable by ear as well as eye), or bombardment, etc. (from examination of shell dumps, etc.). VIII. Position of machine guns (Pill-boxes or other), mortars, etc. IX. Condition of intervening ground and of the wire entanglements. X. Effects of recent bombardments. XI. Moral of the enemy. RECONNAISSANCE FOR OCCUPATION.--In the Reconnaissance of a Position with a view to occupying it for the purposes of receiving attack, the points to be noted are:--