Heavy Machine Gun (HMG)- Originally, any machine gun designed for heavy sustained firing from a tripod and utilizing a water jacket cooling system around the barrel to dissipate heat, hence the term “heavy”. Examples include the Maxim, Vickers, and Browning 1917A1. Later this term applied to machine guns that fired bullets larger than those used in the issue service rifles. The design of the Stahlhelm was carried out by Dr. Friedrich Schwerd of the Technical Institute of Hanover. In early 1915, Schwerd had carried out a study of head wounds suffered during trench warfare and submitted a recommendation for steel helmets, shortly after which he was ordered to Berlin. Schwerd then undertook the task of designing and producing a suitable helmet3 broadly based on the 15th century sallet, which provided good protection for the head and neck.
After lengthy development work, which included testing a selection of German and Allied headgear, the first Stahlhelms were tested in November 1915 at the Kummersdorf Proving Ground and then field tested by the 1st Assault Battalion. Thirty thousand examples were ordered, but it was not approved for general issue until New Year 1916, hence it is most usually referred to as the “Model 1916”. In February 1916 it was distributed to troops at Verdun, following which the incidence of serious head injuries fell dramatically.