M1 helmet
The M1 helmet is a combat helmet that was used by the United States Armed Forces from 1941 to approximately 1985. Designed to replace the M1917 helmet, a variant of the British Brodie helmet used during World War I, the M1 helmet is known for having been used as the primary American combat headgear during World War II, with similarly extensive use in the Korean War and the Vietnam War. Owing to its extensive use throughout World War II and the Cold War, the M1 helmet has become an icon of the U.S. military, with its design inspiring copies and derivative designs used by other militaries around the world.
In 1985 the PASGT helmet, another similarly iconic and influential combat helmet design, was introduced and the M1 helmet began to be phased out. Some M1 helmets and their derivatives remain in service with several national militaries in the 21st century, although most have been relegated to being part of certain ceremonial uniforms, such as those of honor guards.
History
Development
At the entry of the United States into World War I in 1917, the U.S. military did not have a combat helmet; initially, American Expeditionary Forces personnel were issued British Mk l helmets, while those integrated with French units were issued French M15 Adrian helmets. American production quickly began of an American variant of the Mk I, the M1917 helmet, with some 2,700,000 units produced by the end of the war. At that point, the shortcomings of the M1917, which lacked balance and protection of the head from lateral fire, resulted in a project to produce a better helmet which would also have a distinctively American appearance.Between 1919 and 1920, a number of new designs of helmets were tested by the Infantry Board in comparative trials along with the M1917 and helmets of other armies. One of those designs, the Helmet Model Number 5A, was selected for further study. This was an improved version of the Helmet Model Number 5, developed in 1917 and 1918 by Bashford Dean, the curator of arms and armor at the Metropolitan Museum of Art, which had been rejected during the war because of its supposed resemblance to the German Stahlhelm. Eventually, tests held at Fort Benning between 1924 and 1926 showed that although the Helmet Model Number 5A offered better side protection than the M1917, it was more easily penetrated from above, and in some circumstances the shape of the helmet could interfere with properly holding and firing a rifle. Further ballistic tests at the Aberdeen Proving Ground resulted in the decision to retain the M1917 in 1934, which was then given a redesigned leather cradle and designated the M1917A1 or "Kelly" helmet.
In 1940, with World War II raging in Europe and Asia for a year and the United Kingdom seeking help from North America, it seemed increasingly likely that the United States would be dragged out of non-interventionism and into another war. The Infantry Board resurrected the quest to find a better type of helmet, since the ongoing conflict had shown that the M1917, designed to protect men standing in trenches from falling shell splinters and shrapnel, would be inadequate on the modern battlefield. The board reported:
Accordingly, the board, under the direction of Brigadier General Courtney Hodges, took the M1917 shell as the basis of the new prototype, trimmed off the brim, and added a visor and skirt-like extensions to protect the back and sides of the wearer's head. Rejecting the conventional systems of cradles, the new helmet was given a Riddell type liner and suspension system, based on the contemporary style of football helmet, with an adjustable strap for the nape of the neck to prevent the helmet from rocking. The resulting prototype was designated the TS-3, and the McCord Radiator Company manufactured the first examples from Hadfield steel. In tests, they were found to be able to resist a.45 ACP pistol bullet fired at point-blank range, exceeding the initial specification. The TS-3 was given official approval on June 6, 1941, and was designated "Helmet, Steel, M1". Full-scale production commenced almost immediately.
Service
Over 22 million U.S. M1 helmets were manufactured through September 1945. Production was primarily accomplished by the McCord Radiator and Manufacturing Company and the Schlueter Manufacturing Company; the former developed a method to create an almost eighteen-centimeter-deep bowl in a single pressing, which was considered an engineering milestone at the time. A third manufacturer called Parish Reading is known to have produced a very limited number of M1 helmet shells in 1945.In 1942, the helmet bails were changed from a fixed, welded version to a swivel model along with slight alterations to the shaping of the side brim, while in 1944, the stainless steel helmet rim with a seam at the front was replaced by a manganese steel rim with a rear seam. Further M1 helmets were manufactured for the Korean War.
Following World War II, the M1 helmet was widely adopted or copied by numerous other countries and its distinctive shape was adopted as the NATO standard. Postwar analyses of wartime casualty figures by the U.S. Army Operations Research Office found that 54 percent of hits to the M1 helmet failed to penetrate, and estimated that 70,000 men had been saved from death or injury by wearing it.
Production continued during the Cold War era with periodic improvements; in 1955 a grommet in the front of the liner was deleted, in 1964 the liner construction was changed to laminated nylon, and in 1975 a new chinstrap design was introduced. The final contract for U.S. M1 helmets was placed in 1976. The M1 was phased out of U.S. military service during the 1980s in favor of the PASGT helmet, which offered increased ergonomics and ballistic protection.
Design
The M1 is a combination of two "one-size-fits-all" helmets—an outer metal shell, sometimes called the "steel pot", and a hard hat–type liner nestled inside it featuring an adjustable suspension system. Helmet covers and netting would be applied by covering the steel shell with the extra material tucked inside the shell and secured by inserting the liner.The outer shell should not be worn by itself. The liner can be worn by itself, providing protection similar to a hard hat, and was often worn in such fashion by military policemen, Assistant Drill Instructors, and rifle/machine gun/pistol range staff, although they were supposed to wear steel at the range. The liner is sometimes worn in U.S. military ceremonies and parades, painted white or chromed. The depth of the helmet is, the width is, and length is, the steel shell thickness is, The weight of a World War II-era M1 is approximately, including the liner and chinstrap.
Shell
The non-magnetic Hadfield manganese steel for M1 helmet shells was smelted at the Carnegie Steel Company or the Sharon Steel Company of Pennsylvania. After being poured into fifteen-ton ingots, the steel was divided into 216-inch by 36-inch by 4-inch blocks, known as "lifts," which were then cut into three equal 72-inch pieces to make them easier to handle. The cut lifts were sent to the Gary Works in Gary, Indiana for further processing, after which they were each reduced into 250 68-inch by 36-inch by 0.044-inch sheets, which were cut into 16.5-inch circles. The helmet discs were oiled and banded into lots of 400 for delivery by rail to McCord or Schlueter for pressing and final assembly.Each "heat" of steel was assigned a unique number by the smelter, as was each of its "lifts". When each new heat was unloaded at McCord or Schlueter, it was assigned a sequential number, and each lift within the heat was assigned a letter of the alphabet. This unique "lot and lift" number was stamped onto each helmet produced from the discs of a particular lift, and allowed for traceability in case the helmets exhibited defects. The "lot and lift" number is in reference to the time when the fabricator received the helmet discs, not when they were made into finished helmets. Lifts of heats were not loaded onto or unloaded from railcars in any particular order, and were often warehoused before being finished.
M1 helmet shells manufactured during World War II can be identified by these 'lot and lift' numbers. Shells made by McCord during World War II will typically have a 2, 3, or 4 digit number followed by the 'lift' letter. Shells made by Schleuter will have a 2 or 3 digit number followed by a 'lift' letter and a large 'S' can be found beneath the number. Both McCord and Schleuter heat stamps are typically found on the interior of the shell and beneath the front brim. Parish Reading shells can be identified by a heat stamp that is located to the side, underneath one of the swivel loops. These heat stamps always have a 'P' prefix and the heat stamps 'P1' through to 'P6' have been discovered as of 2025.
The helmet discs were drawn to a depth of seven inches to create the rough helmet shape, or "shell," and the edges were trimmed. The edge of the shell has a crimped metal rim running around it, which provides a smooth edge. This is usually known as the "rim". The rim has a seam where the ends of the strip meet. On the earliest shells the seam met at the front. This was moved to the back of the rim in November 1944 At this time, the rim also went from being made of stainless steel to manganese steel. On each side of the shell, there are stainless steel loops for the chinstrap. Early-war production shells had fixed rectangular loops, and mid-war to 1960s helmets feature movable rectangular loops; this feature was adopted in 1943 to address the problem that when earlier helmets were dropped, the fixed loops were more susceptible to breaking off. Early shells for paratrooper helmets feature fixed, D-shaped loops. The shells were then painted with flat Olive Drab shade 319 or Munsell Y10 green paint, with the paint on the outside of the shell sprinkled with either finely ground cork or silica sand.
file:Albert Hoeben RMWO.jpg|thumb|upright|An M1 helmet with camouflage cover worn by a Netherlands Marine Corps corporal in 1945
World War II-production helmets feature sewn-on cotton web olive drab shade 3 chinstraps, replaced gradually throughout 1943 and 1944 with olive drab shade 7 chinstraps. 1950s and later production chinstraps are made of olive drab webbing attached to the loops with removable metal clips. Nylon chinstraps were introduced in the U.S. military in 1975. These straps featured a two-piece web chin cup and were fastened by a metal snap rather than buckle.
Many soldiers wore the webbing chinstraps unfastened or looped around the back of the helmet and clipped together. This practice arose for two reasons: First, because hand-to-hand combat was anticipated, and an enemy could be expected to attack from behind, reach over the helmet, grab its visor, and pull. If the chinstrap were worn, the head would be snapped back, causing the victim to lose balance, and leave the throat and stomach exposed to a knife thrust. Secondly, many men incorrectly believed that a nearby exploding bomb or artillery shell could cause the chinstrap to break their neck when the helmet was caught in its concussive force, although a replacement buckle, the T1 pressure-release buckle, was manufactured that allowed the chinstrap to release automatically should this occur. In place of the chinstrap, the nape strap inside the liner was counted on to provide sufficient contact to keep the helmet from easily falling off the wearer's head.
The design of the bowl-like shell led to some novel uses: When separated from the liner, the shell could be used as an entrenching tool, hammer, washbasin, bucket, bowl, or seat. The shell was also used as a cooking pot, but the practice was discouraged as it would make the metal alloy brittle.