the barbed wire entanglements in no man's land (although it has been suggested that the reason for the use of shrapnel as a wire-cutter at the Somme was because Britain lacked the capacity to manufacture enough HE shell). This perception was reinforced by the successful deployment of shrapnel shells against Germany's barbed wire entanglements in the 1915 Battle of Neuve Chapelle, but the Germans thickened their barbed wire strands after that battle. As a result, shrapnel was later only effective in killing enemy personnel; even if the conditions were correct, with the angle of descent being flat to maximise the number of bullets going through the entanglements, the probability of a shrapnel ball hitting a thin line of barbed wire and successfully cutting it was extremely low. The bullets also had limited destructive effect and were stopped by sandbags, so troops behind protection or in bunkers were generally safe. Additionally, steel helmets, including both the German Stahlhelm and the British Brodie helmet, could resist Shrapnel bullets and protect the wearer from head injury: ... suddenly, with a great clanging thud, I was hit on the forehead and knocked flying onto the floor of the trench... a shrapnel bullet had hit my helmet with great violence, without piercing it, but sufficiently hard to dent it. If I had, as had been usual up until a few days previously, been wearing a cap, then the Regiment would have had one more man killed. A shrapnel shell was more expensive than a high-explosive one and required higher grade steel for the shell body. They were also harder to use correctly because getting the correct fuze running time was critical in order to burst the shell in the right place. This required considerable skill by the observation officer when engaging moving targets. An added complication was that the actual fuze running time was affected by the meteorological conditions, with the variation in gun muzzle velocity being an added complication. However, the British used fuze indicators at each gun that determined the correct fuze running time (length) corrected for muzzle velocity. Replacement by high-explosive shell With the advent of relatively insensitive high explosives which could be used as the filling for shells, it was found that the casing of a properly designed high-explosive shell fragmented effectively . For example, the detonation of an average 105 mm shell produces several thousand high-velocity (1,000 to 1,500 m/s)