The armies of the great powers began to issue steel helmets during World War I as a result of combat experience and experimentation.

Only some types of cavalry retained a metal helmet, albeit these were designed to protect against sabre blows rather than the causes of injury that would become prevalent in the war.

With the growing prevalence of artillery and the widespread adoption of trench warfare, the proportion of casualties on all sides suffering head injuries rose dramatically.

Stationed in the rocky area of the Vosges, Army Detachment Gaede recorded significantly more head injuries caused by stones and shell fragments than other units elsewhere.

The artillery workshop of the Army Detachment developed a helmet that consisted of a cloth and leather skullcap with a steel plate (6 mm thickness).

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 helmet,[4] broadly based on the 15th-century sallet, which provided good protection for the head and neck.

Versions of the M1935 Stahlhelm were sent to Republic of China from 1935 to 1936 and the M1935 was the main helmet of the Chinese Nationalist Army (especially the "central" divisions) during World War II.

In the Socialist Federal Republic of Yugoslavia, due to large quantities captured by World War II Partisans, the Stahlhelm was used in Yugoslav People's Army up to 1959, when it was phased out and replaced by the M59/85 steel helmet.

The M1916 design had side-mounted horn-like ventilator lugs which were intended to support an additional steel brow plate or Stirnpanzer, which saw limited use only by snipers and trench raiding parties, as it was too heavy for general use.

Reserve Lieutenant Walter Schulze of 8th Company Reserve Infantry Regiment 76 described his combat introduction to the helmet on the Somme, 29 July 1916: ... 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.

The large, flared skirt tended to make it difficult for soldiers to hear, distorting surrounding sounds and creating an echo when the wearer spoke.

[19] The formation in 1917 by the Ottoman Empire of stormtrooper battalions following the German model prompted the requirement for steel helmets, as these had not previously been adopted.

The missing front visor was thought by the Germans to be for religious reasons,[22] and it was claimed that it was to allow Turkish soldiers to touch their foreheads to the ground during prayer, without removing their helmets.

It was put into limited production following favourable field tests in early 1933 and small numbers were issued to Reichswehr infantry, artillery and communications units.

It was removed from service following the introduction of the M1935 helmet and most of the remaining stock were reissued to civil organizations such as fire brigades and police forces.

The company "Eisenhüttenwerke Thale" (today Thaletec) carried out prototype design and testing, with Dr Friedrich Schwerd once again taking a hand.

Finally, a completely new leather suspension, or liner, was incorporated that greatly improved the helmet's safety, adjustability, and comfort for each wearer.

In 1938, the Germans developed a variant of the Stahlhelm with a wider, flared peak and ventilation holes originally intended for civil defense and Luftschutz personnel.

[24][25] Known as the gladiator pattern, the privately purchased Luftschutz helmet was originally made from three pieces of steel and typically painted black or dark blue.

[30] A variant of the M1935 helmet with a shell lacking the projecting visor and deep flared rim was issued to Fallschirmjäger (German paratrooper) units.

It was so designed in order to lessen the risk of head injury on landing after a parachute jump; also to reduce the significant wind resistance and resulting neck trauma.

[31] The modified shell also incorporated a completely different and more substantial liner and chinstrap design that provided far more protection for German airborne troops.

Shell paint colours were typically matte grey-green (Heer) or grey-blue (Luftwaffe), and the decals were eliminated in 1943 to speed up production and reduce the helmet's combat visibility.

The East German leadership was motivated in large part by a desire to avoid provoking the offence that using a traditional Stahlhelm design would have caused East Germany's Warsaw Pact allies (especially Czechoslovakia, Poland and the Soviet Union),[15] but a more practical military necessity was also present due to the continued use of surplus Stahlhelme by West German units, in particular border guards.

Moreover, the East Germans suspected the West could re-issue the Stahlhelm on a general basis in the Bundeswehr at any time and therefore needed a helmet that was easily distinguishable from that of their potential enemy.

After Stahlhelm shells were painted, the colours of which varied by organization, small identification or insignia decals usually were affixed to one or both sides of the helmet.

[citation needed][36] The right side of early M35 helmets bore the tricolored shield of black, white, and red stripes, the traditional national colors of the pre-WWI German Empire (cf.

The left side of the shell often received decal insignia denoting the branch of the armed forces, or Wehrmacht, or an organization within the Nazi Party.

The SS was both a paramilitary and a political organization, and its black runic initials on a silver-coloured shield (normally applied to the right side of the shell) looked like twin lightning bolts.