became less an art than a science that could reliably deliver plunging fire at approximately twice the maximum effective range of hand-held weapons of identical calibre, but not so convincingly a belief to hold that the machine gunners were in effect hiding behind the front lines while uselessly firing into the air, making a show instead of dying beside riflemen whose weapons used practically identical ammunition. This conviction may explain–from both sides–the persistence with which machine gunners were placed in exposed positions where their fire was only marginally effective but enemy troops could be seen to fall victim to it, and the great personal bravery with which those same men fought when the same enemy concentrated their forces against the greater threat represented by an unsupported sandbag emplacement. As stated by Paul Cornish in Machine Guns and the Great War: "The theory behind this technique had long been understood... as early as 1908... the mathematical work required to provide a reliable basis for the conduct of such fire was carried out by a group of British enthusiasts at the Hythe musketry school... However, it was 1915 before such fire was successfully carried out in the field..." Cornish goes on "To conduct such fire the proposed target would be located... the relative position of the machine gun relative to it would be determined with ruler and protractor.. calculations would be made to determine the gun's potential cone of fire and the trajectory of its bullets (an important consideration if firing over the head of friendly troops). A clinometer, combined with a graduated elevation dial fitted to the tripod would be employed to set the gun to the correct elevation..." The obvious complexities and the exacting preparations - in effect identical to those of artillery gunners - may have seemed arcane and pointless to those who carried - or whose men carried - rifles firing the same ammunition but could neither see (or more importantly imagine) the terminal effect of a long-range barrage. When properly employed it was unarguably a devastating deterrent, as witnessed by those who took the trouble to seek out the areas interdicted but for those who took the trouble to do so were often regarded uncritical advocates of novel, untried tactics. While in the more sustained direct fire role, properly supported: The 100th Company of the Machine Gun Corps at High Wood on August 24, 1916 was ordered