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.

[3] Consequently, the French staff ordered development of a metal helmet that could protect soldiers from the shrapnel of exploding artillery shells.

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.

[8] In addition to the helmet, a set of armored "epaulets" were also developed by Adrian and issued to defend against shrapnel and air-dropped darts, although they were not in common use.

However, it was found that if the helmet was pierced by shell splinters, pieces of dirty cloth were carried into the wound, which increased the risk of infection.

It was also used by some of the American divisions fighting in France, including the African-American 369th Infantry Regiment, commonly known as the Harlem Hellfighters,[9][10] and the Polish forces of Haller's Blue Army.

[11] The French Gendarmerie mobile adopted a dark blue version in 1926,[12] and continued to wear it into the 1960s, well after the regular army had discarded it.

In December 1915, Winston Churchill (later to become Prime Minister of the United Kingdom from 1940 to 1945), while serving as a major with the British Army's Grenadier Guards, was presented with an Adrian helmet by the French General Émile Fayolle.

[7] They were widely adopted by other countries, including Albania, Belgium, Brazil, China, Czechoslovakia,[14] Greece, Haiti, Italy (including license-built versions), Japan, Latvia,[15][16] Luxembourg, Mexico, Morocco, Peru, Poland, Romania, Russia, Serbia, Spain, Siam, Turkey,[17] the United States, USSR, and Yugoslavia, many of these states adding their own insignia to the front of the helmet.