The Adrian helmet () was an influential design of combat helmet originally produced for the French Army during World War I. Its original version, the M15, was the first standard helmet of the French Army and was designed when millions of French troops were engaged in trench warfare, and head wounds from the falling shrapnel generated by indirect fire became a frequent cause of battlefield casualties. Introduced in 1915, it was the first modern steel helmet and it served as the basic helmet of many armies well into the 1930s. Initially issued to infantry soldiers, in modified form they were also issued to cavalry and tank crews. A subsequent version, the M26, was used during World War II. History World War I At the outbreak of World War I in August 1914, soldiers in the French Army wore the standard kepi cap, which provided no protection against injury. The early stages of trench warfare proved that even basic protection of the head would result in a significantly lower mortality rate among front-line soldiers. By the beginning of 1915, a rudimentary steel skull-cap (calotte métallique, cervelière) was being issued to be worn under the kepi. Consequently, the French staff ordered development of a metal helmet that could protect soldiers from the shrapnel of exploding artillery shells. Since soldiers in trenches were also vulnerable to shrapnel exploding above their heads, a deflector crest was added along the helmet's axis. Branch insignia in the form of a grenade for line infantry and cavalry, a bugle horn for chasseurs, crossed cannon for artillery, an anchor for colonial troops and a crescent for North African units was attached to the front. Contrary to common misconception, the M15 helmet was not designed to protect the wearer from direct impact by rifle or machine gun bullets. The resulting headgear was credited to Intendant-General Louis Auguste Adrian. The helmet adopted by the army was made of mild steel and weighed only ), which made it lighter and less protective than the contemporary British Brodie helmet and the German Stahlhelm. Orders were placed for the helmets in the spring of 1915, which started being issued by July. By September, all frontline troops in France were issued with the helmet. The helmet was surprisingly complex to produce with seventy stages involved in its production, not including those required to prepare the metal. The slot for the badges and the distinctive