DISTANCE.--The distance of the Outpost position from the troops protected is regulated by the time the latter will require to prepare for action and by the importance of preventing the enemy's field artillery from {132} approaching within effective range of the ground on which these troops will deploy if attacked. Heavy guns and mortars, although motor traction gives them great mobility, are unlikely to accompany the enemy's Advanced Guard, and preparation to withstand or prevent their fire will not usually be required from Outpost troops. The effective range of shrapnel is 5,500 yards, the limit of the effective range of machine guns is 2,000 yards, and of Lewis guns and rifles the effective limit is 1,400 yards. The position on which the Main Body will deploy will thus be protected from the shrapnel of field artillery, if the possible fire-positions of that arm are brought under effective fire from machine guns 3,500 yards from the Position of Deployment, with Lewis guns and rifles about 500 yards further forward. On the other hand, especially in the case of small forces (against which artillery will not be likely to be sent), the distance must not be such as would permit of the Outposts being cut off, or as would necessitate the employment of an undue proportion of men on Outpost duty. THE OUTPOST COMMANDER.--Before halting, a commander should first decide on his dispositions in case of attack, and then arrange the quartering of his command and the general position of the Outposts. In the case of a small independent force the commander of the force will usually himself detail the whole of the Outpost troops, and will either retain the command in his own hand or appoint an officer to command them, In such a case the disposition of the troops will probably be that of a perimeter camp, preparation being made against attack from all directions. In the case of large bodies Outpost troops will usually consist of all arms, and a definite commander will always be appointed. This commander will, when necessary, divide the Outpost line into sectors, delegating responsibility for the holding of each sector to the commander of a subordinate unit or formation, and defining the limits {133} of sectors by distinctive features such as trees, cottages, or streams. The tops of hills or the bottoms of valleys are not suitable as tactical boundaries, and roads should be inclusive to one or other sector, for a road used as a boundary may be neglected by one of the commands it divides under the impression that it is the duty of the other command to patrol it. INFORMATION AND ORDERS.--The Outpost commander must have definite information on the following points:-- I. What is known of the enemy and information concerning friendly bodies of troops working against the enemy.