The form of intrenchment, if any, excavated round the bivouac, is conditioned by the character of the enemy.
If he is prone to adopt shock tactics, and to attempt to rush the camp under cover of darkness, a ditch to check his charge, backed by a parapet with head cover, will be the most favourable form of defence.
But if he is partial merely to harassing methods, such as firing into camp, the perimeter defences should be calculated to mitigate their effects, by providing, for all troops, trenches well traversed, and with parapets both to front and rear.
If both forms of attack are possible, parapets with trench and ditch should be made, the trench, or ditch, being first dug, according as a charge or sniping is most to be feared.
Naturally units protected by high ground on one or more flanks, need only make cover so as to secure themselves from the directions from which fire can be delivered.
Only infantry should hold the perimeter of a camp, machine guns being placed at the angles, and the defence of each confided to one unit, divided responsibility not being permissible.
Supports may, if necessary, be located in intrenchments behind the perimeter, and a homogeneous body of about half a battalion, allotted as reserve, and given a bivouac near that of the column commander.
In case of attack, the duty of cavalry soldiers is to stand to their horses, of artillery to man their guns. To neither, therefore, in normal circumstances, should a portion of the perimeter be confided, and both should be placed within its circumference.
At the same time, guns should be so disposed, in pits or epaulments, that they can sweep ground across which attack is most likely to be made; or they may be laid so as to search localities where tribesmen may collect prior to delivering an assault.