U.S. M1 Helmet

The U.S. M1 helmet was the standard issue steel helmet of the U.S. armed forces from 1941 to 1985. The M1 helmet is a world icon of the American soldier. Its design was adopted by the armed forces of many other countries.

The M1 helmet was adopted in July 1941 to replace the outdated First World War M1917A1 “Kelly” helmet, after research and recommendation by Major Harold G. Sydenham of the U.S. Army. The M1 helmet was produced by the McCord Radiator and Manufacturing Company of Detroit, Michigan, and the Schlueter Manufacturing Company of Janesville, Wisconsin. Over 22 million U.S. M1 steel helmets were manufactured from June 1941 through September 1945.

A second US production run of approximately one million helmets was manufactured in 1966–1967. These Vietnam War helmets were different from the Second World War–Korean War helmets by having an improved chin strap, and a steel shell painted light olive green.

The M1 helmet was phased out during the 1980s, and replaced in 1985 by the Personnel Armor System for Ground Troops (PASGT) helmet and ballistic vest, used by the U.S. armed forces from the early 1980s until the mid-2000s. The PASGT helmet and vest were later replaced by the Lightweight Helmet (LWH), Modular Integrated Communications Helmet (MICH), and Interceptor Body Armor (IBA).

As of 2018, the only remaining U.S. military users of PASGT in any capacity are the U.S. Army Reserve and the U.S. Navy, which retains the PASGT helmet for use by sailors aboard its warships, in addition to a PASGT-derived vest known as the “U.S. Navy Flak Jacket”.

Although now long obsolete in the United States, the M1 helmet, and its variants produced in other countries, are still in use by many other nations around the world. In Israeli service, for example, reserve soldiers have used the M1 helmet in combat as late as 2006.

The M1 Helmet Outer Steel Shell

The M1 helmet consists of two “one-size-fits-all” helmets — an outer steel shell, sometimes called the “steel pot”, and a “hard hat” laminated fiber liner that fits inside the steel shell. The liner contains the suspension system that can be adjusted to fit the wearer’s head.

The M1 helmet was drawn to a depth of 7 inches (180 mm) to create the steel “shell.” Width is 9.5 inches (240 mm), and length is 11 inches (280 mm). The thickness of the steel is 1/8″ (3 mm). The weight of a World War II–era M1 helmet is approximately 2.85 pounds (1.29 kg), including the liner and chin strap.

The M1 helmet shell is made of non-magnetic Hadfield manganese steel, an alloy steel containing about 13% manganese, known for its hardness, toughness, and high impact strength. Hadfield manganese steel, also known as Mangalloy, was created by Robert Hadfield in 1882, and is the first alloy steel.

M1 helmet steel was smelted at the Carnegie Steel Company of Pittsburgh, Pennsylvania, and the Sharon Steel Company of Farrell, Pennsylvania.

The edge of the helmet shell has a crimped metal rim running around it, which provided a smooth edge. The rim has a seam where the ends of the rim meet. On the earliest helmet shells, manufactured from July 1941 to November 1944, the seam met on the helmet’s front rim. This seam was moved to the back of the rim in November 1944. The rim, at this time, was also changed from being made of stainless steel to manganese steel.

No distinction in nomenclature within the United States Army supply system existed between early wartime “front seam” helmets and late wartime, “rear seam” helmets. The original Second World War steel helmet shells remained in use until the M1 was retired from service in 1985.

On each side of the shell are stainless steel loops to attach the chin strap. Early World War II helmets have fixed, rectangular loops. Mid–war to 1960s helmets have movable rectangular loops. This improvement was adopted in 1943 to correct the problem of the fixed loops being broken when helmets were dropped. Early shells for paratrooper helmets had fixed, D-shaped loops.

Second World War M1 helmets were painted with flat olive drab paint, mixed with finely ground cork, that produced a rough textured, flat finish. Post-war helmets were painted with a lighter olive green paint, mixed with finer silica sand, that produced a smoother textured, flat finish.

Second World War production helmets used sewn-on darker olive drab (Shade 3) cotton web chin straps, that were gradually replaced throughout 1943 and 1944 with clip-on lighter olive drab (Shade 7) cotton web chin straps.

M1 helmets of the 1950s, and later production helmets, had chin straps made of olive drab webbing attached to the loops with removable metal clips. Nylon chin straps were introduced in the 1980s. These straps had a two-piece web chin cup, and were fastened by a metal snap rather than a buckle.

Most soldiers wore the webbing chin strap unfastened, wrapped around the back of the helmet, with the metal ends clipped together. This practice arose because in hand-to-hand combat, enemy soldiers could be expected to attack from behind, reaching over the helmet, grabbing its visor, and pulling from behind. With the chin strap worn, the wearer’s head would be snapped back, causing the victim to lose balance, and leaving the throat and stomach exposed to a knife thrust.

Also, some soldiers believed that a nearby bomb or artillery shell explosion could cause the chin strap to break their neck when the helmet caught the force of the concussion blast. A replacement buckle, the T1 pressure-release buckle, was later manufactured that allowed the chin strap to release automatically.

In place of the chin strap, the nape strap inside the back of the liner, provided sufficient contact to keep the helmet from easily falling off the wearer’s head.

When separated from the liner, the shell could be used as an entrenching tool, hammer, washbasin, bucket, seat, and for many other practical uses. Soldiers are very creative. The steel helmet shell could also used as a cooking pot, though this was discouraged, because the metal alloy could become brittle when heated.

The First Type of M1 Helmet Liner

The initial U.S. government purchase order for the first M1 helmet liners was issued on July 9, 1941. The original M1 helmet liner was designed by the Hawley Products Company of St. Charles, Illinois, relying on the company’s prior experience in manufacturing tropical sun helmets for the army. The Hawley Products Company worked in cooperation with the McCord Radiator & Manufacturing Company of Detroit, Michigan, and the U.S. Army Quartermaster Corps.

The first M1 helmet liners were constructed of two rigid fiber shells made from compressed paper, impregnated with phenolic resin, securely cemented together, and covered with dark olive drab cotton twill fabric.

The suspension system was an adaptation of one developed by John T. Riddell for his famous plastic football helmet. In 1939, at the beginning of the new plastics industry, John Tate Riddell invented and patented the webbed helmet suspension. His plastic football helmet design, with webbed suspension, ultimately replaced the leather football helmets then in use. In June 1941, at the request of the U.S. Government, Riddell granted a license to use his suspension in the production of military helmets and liners.

John Riddell died on July 3, 1945, and never lived to see his football helmet become the most popular football helmet ever made.

The first M1 helmet liner suspension was made with lightweight strips of silver-gray rayon webbing, stretched across and around the inside of the liner. The headband was non-adjustable and was supplied in 13 sizes. The neckband was also non-adjustable and came in 3 sizes. The leather chin strap was permanently attached.

A sweatband clipped to the webbing could be adjusted to fit around the wearer’s head. Three triangular bands of rayon met at the top of the helmet, where they were adjusted by a shoestring to fit the height and shape of the wearer’s head. The rayon had a tendency to stretch and not recover its shape, so the suspension material was changed to dark olive drab (Shade No. 3), and later to light olive drab (Shade No. 7), herringbone twill cotton webbing. A snap-on nape strap cushioned the liner against the back of the wearer’s neck.

The first type of M1 helmet liner shell, made by the Hawley Products Company, degraded quickly in the field under high heat and humidity conditions. The first type helmet liner was discontinued after a production run of only five months, from July to November 1942. When production ended, a total of 3,900,000 of these early liners had been produced.

The Second Type of M1 Helmet Liner

From the beginning, the original Hawley cloth-covered fiber helmet liner was regarded as an expedient, interim liner. It served to make the new steel helmet shell usable until a better plastic liner could be developed. The second half of 1941 was spent in plastic liner research. During comparison testing from late 1941 to early 1942, researchers studied liners made by different processes. By November 1941, it was determined that the best type of liner was made using “high-pressure” laminated plastic.

This second type of M1 helmet liner was made using the “low pressure” manufacturing process developed by the Inland Division of General Motors of Dayton, Ohio. The liners were made by the St. Clair Rubber Company of Marysville, Michigan, and the Hood Rubber Company of Watertown, Massachusetts. These low-pressure laminated plastic liners were made with strips of cotton cloth, impregnated with phenolic resin, draped in a star pattern, and pressed over a liner-shaped mold.

Although this “low-pressure” process was inferior to the “high-pressure” process, and the liners produced were not considered acceptable by the Army, the “low pressure” manufacturing process was continued out of need. In total, the manufacturers were given contracts to make 1,300,000 M1 helmet liners.

By late Spring 1942, an improved suspension system had been designed. The suspension system of the second M1 helmet liner was made of light olive drab (Shade No. 3) single herringbone cotton twill webbing. The rectangular metal washers that held the original rayon suspension system to the original fiber liner were changed to A-shape metal washers. The headband was now adjustable, and was entirely covered with leather for wearer comfort, except in the adjustment area. The leather chin strap was now removable and more substantial.

Helmet liners have brown leather chin straps. Early chin straps were riveted directly to the inside of the liner. Later chin straps were snapped onto studs, and could swivel inside the liner. The chin strap was usually looped over the front rim of the steel helmet shell.

The Third Type of M1 Helmet Liner

By early 1944, the new “high pressure” process that produced better-quality helmet liners was finally adopted. Companies that produced “high pressure” liners during World War II included Westinghouse Electric & Manufacturing Company of Pittsburgh, Pennsylvania, Firestone Tire and Rubber Company of Nashville, Tennessee, CAPAC Manufacturing Corporation of Capac, Michigan, Inland Division of General Motors of Dayton, Ohio, Mine Safety Appliances Company of Cranberry Township (Pittsburgh), Pennsylvania, Seaman Paper Company of Gardner, Massachusetts, and International Molded Plastics, Inc. of Jackson, Mississippi.

Between 1951 and 1954, during the Korean War, the Micarta Division of Westinghouse and CAPAC Manufacturing Corporation made helmet liners, nearly identical in construction to the “high pressure” helmet liners of the Second World War.

In the 1960s, the M1 helmet liner was redesigned, eliminating the leather chin strap, nape strap, and changing the suspension webbing to a pattern resembling an asterisk, using a coarse cotton web material instead of the earlier cotton herringbone twill. In the early 1970s, suspension materials were again changed to a thicker, more flexible nylon with a rougher unbeveled rim. Later changes included a move to a yellow and green material for liner construction.

M1 helmet liners used by paratroopers used a different suspension design. The short piece of webbing that held the nape strap at the back of the helmet liner was extended around the sides of the liner, and terminated on each side in inverted “A” shaped yokes that hung down below the rim of the liner, with buckles for an adjustable chin cup of molded leather. Two female snaps inside the liner above the inverted “A” yokes accepted male snaps on each of the steel shell’s chin straps, to help steady the liner inside the steel shell during abrupt, violent movements.

The outer steel helmet shell was never worn by itself, although the laminated fiber liner was often worn by itself, providing protection similar to a hard hat. The liner was often worn by military policemen, drill instructors, and weapons firing range monitors. The M1 helmet liner continues to be worn in U.S. military ceremonies and parades.

M1 Helmet Covers

Helmet covers and netting were used to cover the steel helmet shell, with the extra material tucked inside the shell and secured by the liner.

In late 1942, the United States Marine Corps used a cloth helmet cover with a camouflage pattern for its helmets. The cover was made from cotton herringbone twill fabric. It had a “forest green” pattern on one side and a “brown coral island” pattern on the other.

The United States Army often used nets to reduce the helmets’ shine when wet, and to allow burlap scrim or vegetation to be added for camouflage purposes. Most nets were acquired from British or Canadian army stocks, or cut from larger camouflage nets. The U.S. army did not adopt an official issue net until the “Net, Helmet, with Band” that included an elastic neoprene band to keep it in place.

After the Second World War, various styles of camouflage covers were used at different times. In the 1960s through 1970s, for the first time, the cloth camouflage helmet cover became a general issue item within the army. The type commonly seen in the U.S. Army and Marine Corps was a reversible fabric cover called the Mitchell Pattern, with a leafy green pattern on one side and orange cloud pattern on the other.

This type of helmet cover was used everywhere in Vietnam, with the green portion of the reversible fabric camouflage normally worn outermost.

Helmet covers, with the (European) woodland camouflage pattern, were designed for fighting in the (NATO) European Theater of Operations. This cover became the post-Vietnam (jungle pattern) camouflage cover used by the U.S. armed forces from the late 1970s onward.

The (European) woodland pattern was printed on one side only, and was not reversible. Some rare desert camouflage examples do exist. These covers were made from two semi-circular pieces of cloth stitched together to form a dome-like shape conforming to the helmet’s shape.

Helmet covers were secured to the helmet by folding the open ends of the cover into the steel shell, then placing the liner inside the shell, trapping the cloth between the shell and the liner. An olive green elastic band, intended to hold additional camouflage materials, was often worn around the helmet to further hold the cover in place.

Other armies used these or similar covers printed with different camouflage patterns, or employed entirely different methods. In the Dutch Army, for example, it was common practice to use a square piece of burlap as a helmet cover on M1 helmets, usually secured by a net, and a wide rubber band.

During the Battle of the Bulge in December 1944, and later in the Korean War (1950-1953), soldiers made their own white camouflage helmet covers for use in winter conditions. White helmet covers were not issued to soldiers, so the soldiers simply made their own winter camouflage covers from any white cloth available, from a shirt or tablecloth, or parachute canopy.

The original version of the M1 helmet liner was manufactured by the Hawley Products Company of St. Charles, Illinois. The Hawley Company, working with the McCord Radiator & Manufacturing Company of Detroit, and the Quartermaster Corps, designed this liner, relying on their prior experience in manufacturing tropical sun helmets for the army. The liner was constructed of two rigid fiber shells, impregnated with water-repellant materials, securely cemented together and covered with olive drab twill.		The suspension system was an adaptation of one developed by John T. Riddell for his plastic football helmet and was made of lightweight silver-grey rayon webbing. The headband was non-adjustable and was supplied in 13 sizes. The neckband was also non-adjustable and came in 3 sizes. The leather chinstrap was permanently attached. The initial purchase order for these liners was issued on 9 July 1941. By mid-November of 1942 when production was terminated, 3,900,000 of these fiber liners has been produced.		As improvements was developed, they were incorporated into the liners then in production. Generally there was some delay in the installation of the new parts as stocks of the older materials were used up first. Here is the improved Hawley liner.
By late Spring 1942, an improved suspension system had been designed. It was made of light olive drab (Shade No. 3) cotton single herringbone twill webbing. The rectangular metal washers which had held the rayon suspension system to the original fiber liner were changed to an A-shape. The headband was now adjustable, which eliminated the need to stock 13 sizes. It was also now covered with leather entirely, except in the adjustment area, which added to the comfort. The leather chin strap was now removable, and was more substantial. This fiber liner was made sometime between June and November 1942.		The cloth-covered fiber liner was considered from the beginning to be only an interim expedient. It provided the means to make the new steel helmet shell usable until a plastic liner could be developed. The second half of 1941 was spent in plastic liner research. By November, it had been determined that a liner made of plastic, laminated by high pressure, was the best. During comparison testing done in late 1941 and early 1942, liners made by different processes were studied. One of the competitors was this low-pressure plastic liner made by the St. Clair Rubber Company of Marysville, Michigan. Even though their product did not fare as well as the high-pressure liners, the St. Clair Company was given contracts for 1,300,000 liners.		This liner was probably produced in June or July 1942, as it has the improved suspension, and removable chinstrap, but retains the old style non-adjustable headband.
This liner is identical to the transition St. Clair model, except for the improved adjustable headband. The supply of the older style headbands had been depleted by the time this liner was made. These low-pressure plastic liners, as well as those made by the Hood Rubber Company, were used to give the high-pressure liner manufacturers time to work out the difficulties in their production processes. These St. Clair liners were made of resin-impregnated duck cloth, cured under 110 pounds of steam pressure. Note the insignia eyelet in the front of the liner. This eyelet is found on all plastic liners manufactured up to about 1956.		The Hood Rubber Company of Watertown, Massachusetts attempted to make their liners as simple as possible. They used materials which were not critically needed for the war effort. Instead of resin-impregnated duck cloth, used in other plastic liners, the Hood liner was made of high-count cotton sheeting impregnated with resin. This product was cured with hot water under 250 pounds pressure. The Hood engineers believed that they had a liner superior to those made by other methods, but the Army did not concur, and contracted for only 206,000 helmet liners. This particular specimen has been repainted sometime in the past.		This liner has the improved suspension, adjustable headband, and removable chin strap. Note the fine weave of the liner material, as compared with those made from duck cloth. Duck cloth or “cotton duck” is a kind of tightly woven lightweight canvas. It can be light enough to be used for shower curtains, or heavy enough to be used for seabags and hammocks.
The Hood liner had additional cotton sheeting material added at right angles in the front and the back for reinforcing. This additional material can be seen in this view.		Here is an original Westinghouse high-pressure plastic liner. This is one of the earliest examples of the high-pressure liner, possibly being made under the contract of February 28, 1942. The high-pressure liner was fabricated from strips of duck cloth, impregnated with phenolic resin, and laminated under a pressure of 150 tons. The Army chose the Westinghouse design as the best, and the other manufacturers had to adopt that method.		The “high pressure” manufacturing process provided a much smoother inside surface than that of the “low-pressure” manufacturing process. Note that the suspension system is identical to that in the original Hawley fiber liner, including the rectangular washers of the retention rivets. This specimen also has the original permanently attached chin strap.
Here is another early Westinghouse helmet liner. This one was manufactured at a later date than the previous one. Note that the metal washers of the retention rivets have been changed to the A-shape, and the chin strap is removable. This latter feature indicates that this liner was made about June 1942. Helmet liners of this type were also made by Inland Division of General Motors and Mine Safety Appliances Company.		By late Summer 1942, the M1 helmet liner had evolved into the so-called standard World War II model. It was made of high-pressure plastic, had a light olive drab herringbone twill webbing suspension system, adjustable headband, and removable chin strap. The adjustable neckband was not adopted until March 1945. These standard liners were manufactured by Inland Division of General Motors, Westinghouse Electric & Mfg. Co. (Micarta Dept.), Mine Safety Appliances Co., Capac Mfg. Company, Seaman Paper Company, International Molded Plastics, and the Firestone Tire & Rubber Company.		Here is the inside of the previous liner, which was made by the Capac Mfg. Company.
The earliest helmet liners modified for use by paratroops were produced from standard Hawley fiber liners by the McCord Radiator & Manufacturing Company. The first contract was signed on January 24, 1942 for the modification of 8,000 liners. These modified fiber liners are extremely rare today, as very few survived. The first plastic liners for paratroops were made by Inland Division of General Motors under a contract for 75,000.		The light olive webbing inverted A-straps on each side of the liner are secured by the same rivets that hold the suspension system in place. Wire buckles at the points of the inverted A-straps attached the chamois-lined leather chin cup. The female half of a snap fastener is located on the inside bottom edge, between the legs of each inverted A-strap. The chin strap of the paratrooper’s steel helmet shell had an extra web tab on each side, containing the male half of the snap fastener. Fastening the snaps on each side helped to keep helmet and liner together during parachute jumps.		After the contracts awarded to McCord and Inland Division had been completed, Westinghouse became the only producer of paratroop helmet liners. This example is thought to have been made fairly late in the war. Note that the webbing inverted A-straps are made of dark olive drab (Shade No. 7), and that the buckles at the point of the inverted A-straps are made of olive drab-painted cast metal.
The chamois-lined leather chin cup has been abandoned in favor of a webbing chin cup with five metal grommets in each end for adjustment. Later, the number of grommets was reduced to four in each end. According to Marion Massen’s manuscript, the chamois chin cup was changed to a webbing chin cup in the Spring of 1944. The webbing chin cup cost $0.16 each, as opposed to $0.28 each for the chamois chin cup.		Another special liner used in World War II was the one produced for jungle troops. These liners were made only by Westinghouse, and came from their standard production run. The only unusual aspect was the camouflage paint system, developed by Westinghouse. The different camouflage colors were applied by airbrush through templates, using a type of stenciling process. Approximately 10,000 liners could be camouflaged per day. A total of 854,225 jungle troop liners were procured in 1942 and 1943. In March 1944, painting of the camouflaged liners was discontinued, and approximately 300,000 were repainted olive drab. The reason given was that helmet nets were more effective than camouflage paint. This seems rather strange, since nets were usually not worn on liners, and also the liners were generally inside the steel shell in combat anyhow.