may be expected to mass, or from which assault is to be anticipated. This was done at the defence of Chakdara in 1897 with excellent results."
Machine guns are invaluable to the rear guard of a force retiring, which is an exceedingly difficult undertaking in mountain warfare, because hillmen invariably await this opportunity to swoop down and make a vigorous attack. The very nature of the operations necessitates frequent retirements. Callwell says: "Columns have to visit outlying valleys for punitive purposes, and must then rejoin the main body; and even when penetrating into the heart of a hostile mountain district, the rear of the army, as it passes successively the homes of different tribes and clans, draws these down upon it, and, as a result of the general direction of its march, retires before them."
Field Service Regulations, 1909, speaking of rear guards in mountain warfare, says: "Mountain artillery should usually form part of a rear guard, and machine guns may he usefully employed. The withdrawal of the artillery is usually an encouragement to the enemy to press on, and on such occasions machine guns will often find scope for action. . . ." "If the rear-guard commander considers it impossible to reach camp before nightfall, it will generally be advisable for him to halt and bivouac for the night in the most favourable position for defence." Here, again, machine guns will be most useful in defending the bivouac after dark
