The main elements of the strongpoint must be capable of being constructed by a party of reasonable size during the hours of darkness of one night. ¡ The original design must permit of subsequent improve ment and enlargement, and also of connection to neighboring wICES to form a continuous system. 5. Concealment. Revelation of the identity of the strongpoint is most laybe effected by aerial observation and photographs Its OMLment in plan must therefore be studied-this means that its HOTponent parts must not differ from the surrounding trend system 27. i Form: ii Grouping. After a bombardment, the pattern of shell-hi to be spread over a considerable depth from front to rear, thas there is more chance of a strongpoint of some depth being hit than a very shallow one. A strongpoint should therefore be kept a shallow as possible, provided that effective fine is obtained to the flanks. 9. Communication. All trenches leading into the strongpoint must be commanded by a loopholed traverse or similar block, and straight v straightened within bombing distance. 10. Independence. In order that the strongpoint may be capable of independent resistance, it should have a permanent garrison, supplied with stores of ammunition and grenades, food and water, softest at least two days. 11. Flexibility and Simplicity of Design The trace and details of the strongpoint should be the same as those of ordinary fire and communication trenches. It will therefore adapt itself to any ground, and can be constructed by all troops. 12. Elementary Design The elementary design should be for a strongpoint that can reasonably be made under favorable conditions by a party of say one section Field Company, R. E., with half platoon infantry and about 200 carriers working for four to six hours. This period will allow the hours of darkness to be utilized and will obviate the necessity for a relief. (See Appendix.) 13. Elaboration. The original elementary design must be such that the strongpoint can be improved by the construction of deep dug-outs, etc., and enlarged by the addition of extra fire bays. It should also be capable of being joined up with neighboring work, to form a continuous trench system. For the last purpose, it is generally advisable to turn back slightly the flanks of any lateral trenches, so that when joined up, the original strongpoints will form little salients, giving flanking fire. 14. Machine Gun Spots. Another elementary form of strongpoint consists of a machine gun "spot" comprising one or more slits or dug-outs for guns and detachments with covered or open emplacements, preferably the latter. These "spots" should be surrounded by a low wire entanglement and can be connected one to another by narrow communication trenches suitably concealed. (See Sketch G.) In a somewhat similar way a machine gun can be sited in the rear of a shallow strongpoint to cover the flanks of the work; if necessary this gun can be kept in the front line of the strongpoint until the time of the close infantry attack. 15. Buildings. Isolated buildings and their vicinity should be avoided if possible, though concrete machine gun emplacements may be built inside them, with dug-out accommodation below for the detachments. Appendix. Sketch A shows a specimen of the approximate size of strongpoint that could be constructed in one night. The working party is assumed to consist of 1 section of a Field Company, R. E., assisted by a company of infantry. The strongpoint should be constructed by the above party in 42 hours in average soil, in dry weather, if there is no interference by the enemy; this includes excavating that part of the communica |