M5-11-7 Combat Service Mask

M5-11-7
M5-11-7 Army Combat Service Mask
Also	E6-3-7 Army Assault Gas Mask
A D-Day-Era E6 Assault Mask with E3 Canister, E7 Carrier, M1 Shoe Impregnate, Individual Protective Gas Covers, M1 Eyeshields, Anti-Dimming Stick, Gas Detection Brassards, M4 Protective Ointment, and CWS Gas Identification Card.
Preceded by	M3 and M4 Lightweight Service Mask
Succeeded by	M8 Snout-Type Service Mask and M9 Field Protective Mask
Filter	E3/M11
Weight	Approximately 2.8 lbs (1.3 kg)
Filter connection	60mm
Made in	United States
Period	1943-1958
Issued to	US Army Industry
Manufacturer	Edgewood Arsenal (Final Assembly), Assorted Manufacturers (Hardware)

Since the late 1920s, one of the ultimate goals of the American Chemical Warfare Service was the procurement of a specialized mask which reduced the overall weight and size to a convenient package without sacrificing protective quality. Most of these concepts varied from novel at best to bizarre and impractical at worst, because, at the time, it seemed inconceivable for the American Chemical Warfare Service to develop a mask whose canister was mounted directly to the side of the facepiece without causing leaks. The U.S. had dabbled with masks that had canisters mounted in the chin position, but did not hold them to high regard given the inconveniences noticed wearing the mask while lying prone or crawling. In 1941, the British had finalized what would become the Light Anti-Gas Respirator Mk. I, which took the profile of the Civilain Duty Respirator, but successfully mounted a small 60mm-threaded replaceable drum canister on the side of the facepiece. Later, the General Service Respirator Mk. V mould was used to create a much more serviceable Mk. II design.

Taking note of this, the CWS established a research division at the Massachusetts Institute of Technology (MIT) in 1942 to develop a mask based off this pattern while utilizing the then-standard M2, M3, and M4 Service Mask Faceblanks. Many unique concepts came of MIT's experiments in effort to develop an American side-canister mask, but ultimately one would go on to be developed and adopted as the E6-3-7 Army Assault Gas Mask in 1943, filling the gap for a compact, lightweight mask to be used by amphibious landing teams and paratroopers alike during the upcoming Operation Overlord.

Development

Initial MIT concepts for a lightweight "assault" mask with a side-mounted canister ranged from the creative to the bizarre. By June 23, 1943, the bulk of the experimentation was nearing a conclusion and the final pattern for the defining features of an 'assault' mask were realized. These principles involved a side-mounted canister that integrated with the existing deflector channels of a standard service mask facepiece, the canister being 60mm threaded and replaceable, and the carrier being waterproof and convenient to carry.

The E3R4-E1R6-E1R3 (E6-3-7) Assault Mask, with Class 'B' Gray Rubber Faceblank, typical of experimental early procurement examples.

The concept which would go on to be developed further was known as the E4R3-E1R6-E1R3 - the E4R3 facepiece design took a standard Class 'B' Gray M3 Service Mask Faceblank, removed the hose stem, a 2" slot cut in the left deflector channel from the outside, and a blanking plug and canister port were re-vulcanized onto the existing faceblank, allowing for the 60mm E1R6 Canister to thread into the side of the mask and the incoming air channeled into the usual deflector tubes without entering from the bottom. The E1R3 Carrier was made of waterproof, cotton duck canvas, coated on both sides with butyl rubber, whose opening flap was rolled uprightly and closed with 4 ball-and-socket type 'DOT' button fasteners along the exterior.

The MIT E4R3-E1R6-E1R3 was given a limited procurement contract of 250,000 specimens on October 15, 1943, where 1,282 masks were delivered in December of that year. On January 21, 1944, the E3R4 was re-designated the E6-3-7 and continued testing until April of 1944. The E7 Carrier differed little from its prototypical counterpart, and sometime after January 1944, it was recommended that the 4 DOT button fasteners be replaced with 3 'Lift-The-Dot' fasteners, and the carrier be widened by 1/2" width-wise, and 1½" length-wise, resulting in the E7R1 Carrier.

Additionally, the normal M7 Head Harness was found to insufficiently support the E3 Canister while in use, and so the introduction of a canister-supporting nape strap resulted in the C4 Head Harness, and this plus the introduction of slightly smaller faceblank resulted in the E6R1 Facepiece. Despite the presence of the upgraded M7 (E7R1) Carrier being procured by Spring of 1944, and the recommendation to finalize the E6R1-3-E7R1 as the M5-11-7 on May 26, 1944, the plan was set back as the large-scale procurement of 398,462 E6-3-7 Assault Masks was set into production after February 1944, with enough available to go into action during the invasion of Normandy, June 1944.

E6-3-7 Assault Mask

E6-3-7 Army Assault Gas Masks with Poplin Gas Protective Hoods. Notice the model pictured on the left with a right-mounted canister for left-handed shooters - a feature that would never enter full production.

The E6-3-7 initially issued E6R1 Masks utilizing Class 'B' Gray Natural Rubber M3 Faceblanks, however existing stocks of these Gray Rubber M3 Faceblanks were diminishing due to Japanese control over the Pacific cutting the U.S. off from natural rubber, and the procurement of M3-10A1-6 Lightweight Service Masks made of black government rubber neoprene (artificial rubber) after May of 1943 allowed the E6 Mask to be produced of said neoprene M3 Faceblanks. The neoprene E6R1 Facepiece (still referred to as E6 during issue) would fill the bulk of the E6-3-7 Assault Masks issued during the Normandy beach landings and used well into Holland while the E6R1-E3-E7R1 was waiting to be finalized as the M5-11-7 Combat Service Mask.

The E6-3-7 was also issued with an E3 Canister (British Light-type Containers were also authorized in case of short supply), which is identified by the manufacturer marking 'CROWN' or 'C' embossed into the steel body in addition to the 'E3' designation stamp, an E4R2 Mud Guard that prevented debris from clogging the canister inlet, and of course the waterproof E7 Assault Mask Carrier, which would be marked in yellow with the typical US and CWS Logo Markings, followed by U (Universal Size) or UL (Universal Size, Left Canister Stem) and 'Army Assault Gas Mask'. Although there were plans to produce a variation of the E6R1 Mask with a canister stem on the right side of the mask for left-handed shooters (hence the 'UL' Marking on some E7 Carriers), these plans were scrapped as it was realized how difficult it was to produce the E6R1 Mask, and high rejection rates owing to the production priority on the left canister stem model.

M5-11-7 Combat Service Mask

A Typical M5-11-7 Army Combat Service Mask. Note the use of the earlier E7 Carrier, stamped 'Army Combat Service Gas Mask', as per the June 7 Contract Guidelines. New Production M5-11-7 Masks made after this period would receive the M7 (E7R1) Carrier.

On June 7, 1944, the E6-3-7 Assault Gas Mask was standardized as the M5-11-7 Combat Service Mask. The new, larger M7 (E7R1) Carrier, which replaced the 4 DOT Fasteners with 3 Lift-The-Dots began to overtake and replace the earlier E7 Carrier, as did the M11 Combat Canister begin to overtake the E3. However, production of the M5-11-7 Combat Service Mask was halted shortly after due to complications in producing the neoprene faceblanks, in addition to MIT beginning development on a new assault-style gas mask, the E19R25-M11-E19R2.

On top of poor production rates, an Army field test report from January 18, 1944, had discovered that when neoprene E6-3-7 Masks were kept stored and carried in -20°F (-28°C) temperatures for over 20 hours, the rubber would take a permanent set and become so stiff, that it would not properly seal against the user's face should the mask be needed until it was warmed up for at least a minute against the user's body. Additionally, masks that were removed and stored in their carriers after 30 minutes of wear time in -10°F (-23°C ) temperatures were found to have frozen condensate on the M8 Outlet Valves that would make exhaling impossible until enough exhaled breath contacted the valve to make it supple again. This phenomenon of cold-climate stiffening was subsequently referred to as 'cold-set'.

A later M5-11-7 Combat Service Mask with M7 (E7R1) Carrier. Note the 1944-Pattern C15 Exhalation Valve, developed in response to M8 Valves freezing shut in colder climates.

By June 8th of 1944, the Office of Chief Chemical Warfare Officer, Headquarters European Theater of Operations USA began to forward complaints of black neoprene Lightweight and Combat Service Masks experiencing cold-set colder regions of the ETO. By Fall of 1944, the Army then issued an executive order to divert all neoprene masks produced from that point onward to the Pacific Theater of Operations and have all masks made of Class 'B' Grey natural rubber sent to the ETO. On top of this, all available 400,000 remaining M2 Service Masks in the ETO were slated to be converted into M4 Lightweight Service Masks.

Despite this, high rates of rejection on the production line combined with the mask's limited specialty role lead the M5-11-7 Combat Service Mask to cease production in late 1944, owing to 500,000 total E6-3-7 and M5-11-7 Masks produced during the war. The M5 combat Service Mask continued to be experimented with and scantly issued to primarily Airborne units, and continued random issuing as a standard-issue or more commonly as a training mask after WW2 until it was obsoleted entirely from service in 1958 in favor of the M9 Series Field Protective Masks. The M5 mask continued to be utilized by civilians and at the Hanford Plutonium Finishing Plant for a short while into the 1960s, but no official military usage was made of the mask after 1958.

Additional Accessories

The standard packaged accessories for the E6/M5 Masks consist of:

	E6R1 Mask	E3 Canister	M11 Canister	E4R2 Mud Guard	E7 Carrier	M7 (E7R1) Carrier	Anti-Dim Stick or Cloth
E6-3-7 Army Assault Mask	Yes	Yes	No	Yes	Yes	No	Yes
M5-11-7 Combat Service Mask	Yes	No	Yes	No	Yes	Yes	Yes

Additional issued accessories include:

Individual Protective Cover	M1 Eyeshields	M4 Protective Ointment	BAL Eye Ointment	Gas Brassards	Gas Identification Card
2 Issued	1 Issued	1 Issued	1 Issued	2 Issued, One Worn	1 Issued, Optional

E7/M7 Assault Carrier

A Typical E7 Assault Carrier.

Worthy of specific note all on its own is the special rubberized carrier utilized with the E6/M5 Masks. Due to the hermetically watertight construction of the rolled closure flap, the carriers have been reported to double as an impromptu flotation device, credited with saving lives of men dropped into deep water during Operation Overlord. There were many ways the carrier could be worn on the body, including, but not limited to:

• Top Strap Around Shoulder, Bottom Strap Around Waist, Roll Facing Out and Forwards, Carrier at Left Side
• Top Strap Around Waist, Bottom Strap Around Thigh, Roll Facing Out and Forwards, Carrier at Left Thigh
• Top Strap Around Left Shoulder, Bottom Strap Around Right Shoulder, Roll Facing Out and Upwards, Carrier on Upper Chest
• Straps Crossed over Upper Chest, Roll Facing Out and Upwards, Carrier on Upper Back

Many variations, reproductions, and fakes of these carriers also exist and there are ways of determining each one.

	4 DOT Button Fasteners	3 Lift-The-Dot Fasteners	OD103 Strap Webbing	OD107 Strap Webbing	"Army Assault Gas Mask"	"Army Combat Service Gas Mask"
E7	Yes	No	Yes	Yes	Yes	Yes
M7 (E7R1)	No	Yes	No	Yes	No	Yes

Reproduction E7 Carriers.

Reproductions will generally be made of a lower-quality, more plastic-looking rubberized material with garishly bright hunter green or neon yellow stamps. Additionally, these poorer-quality reproductions will typically have paper-thin nylon webbing as the straps and incorrect buckle hardware/sewing patterns. Better quality reproductions will use more convincing rubberized fabric material, but can still be told apart from most originals from the heavy braid pattern of the fabric visible under the rubber coating, looking much like tarp fabric to a degree. Additionally, the markings will still be blatantly bright yellow with inaccuracies in the style of the CWS Logo Stencil. Most of the newer good-quality reproductions will also have OG-103 "Khaki" webbing straps, which was a feature on some early E7 Carriers, but a majority do not and finding originals like this is a rarity.

Cultural Impact

Replica E7 Carriers featured in Saving Private Ryan (1998)

The E6-3-7 Assault Mask is undoubtedly one of the most historically significant masks of the Second World War, although the carrier seems to be more famous than the complete mask itself, as the appearance of wearing the black, rubberized E7 Carrier on the chest of an American GI is one of many iconic symbols of the Normandy Invasion. The E6-3-7 has appeared in many movies, video games, and war documentaries centered around the Omaha Beach Landing, perhaps the most famous being Saving Private Ryan (1998). Due to the mask's historical provenance and its appearance in popular media, it is one of the most valued and sought-after gas masks of the WW2 period, with prices of complete sets ranging between $200-700 on average, depending on the condition and completeness.

Gallery 

E6-3-7 Army Assault Gas Masks being packaged.

An unissued E6-3-7 Army Assault Gas Mask. This example was sold on June 19, 2019 for a total of $595.00 USD.

The E6 As Worn. The canister pictured is not a normal E3/M11 Combat Canister, but an MIT-E10R2 Smoke Canister.

An E6-3-7 Army Assault Mask and all possible gas warfare-related individual accessories.

An E6-3-7 Army Assault Mask (Left) compared to the older M4-10A1-6 Lightweight Service Mask (Right).

Detail on the 60mm Canister Stem and C4 Head Harness of an E6-3-7 Mask.

A Modified M5-11-7 Combat Service Mask with Lens Frames off a Willson G-2 Mask and an M14 Aerosol Filter in use at The Hanford Finishing Plant.

A Rare Class 'B' Gray Rubber E6 Assault Mask with the 1944 Pattern Experimental C15 Outlet Valve.

Side Profile View.

Much of the Same. Notice the Later M11 Combat Canister.

View of the early C4 Head Harness.

The E7 Carrier. It is uncertain whether it lacks any markings or if they have simply worn away.

Mask in the E7 Carrier.

An expired listing photo for the Class 'B' Gray E6 Assault Mask.

Much of the Same.

An E4R3-E1R6-E1R3 Army Assault Gas Mask. This example owned by Flechette Gas Masks

View of the Canister Stem, of which the Threaded Inlet Valve Assembly is of Canadian origin.

The presence of an M7 Head Harness instead of the later C4 confirms this as an E4R3 Facepiece.

Production Stamps. Facepiece mady by the Acushnet Processing Co. on May 1943.

Mask Interior.

Another Typical E6-3-7 Assault Mask. Notice the Unissued E4R2 Mud Guard.

Mask Interior. E6/M5 Masks were produced without inner oronasal cups to streamline production and issuing.

Reverse side of a typical E7 Assault Carrier.

An E6-3-7 Facepiece from the Collection of GasMaskBunker.

An E6-3-7 Facepiece after disassembly, prior to restoration. From the Collection of GasMaskBunker.

An E6-3-7 Facepiece, Post-Restoration, still in need of a new C4 Head Harness. From the Collection of GasMaskBunker.

M5-11-7 Combat Service Mask Kit, from the Collection of GasMaskBunker.

A profile comparison between the M5 (Left) and E19R49 (M9) (Right) Combat Service Masks. From the Collections of GasMaskBunker and RetroRespirators.

Side view, revealing canister stems and deflector paths. Note the harness webbing is not present due to ongoing restoration. From the Collections of GasMaskBunker and RetroRespirators.

A typical, unissued E6-3-7.

References

1. "M7 Army combat Service Gas Mask" - CRAIG PICKRALL FIELD & PERSONAL GEAR SECTION - USMilitariaForum
2. "The Lightweight Service Gas Mask, Carrier, and Accessories in the ETO, Pt 1: The Gas Mask" - 100th Infantry Division (Reenacted)
3. "Saving Private Ryan: M7 Gas Mask Bag" - Saving Private Ryan Online Encyclopedia
4. "M5 Assault Gas Mask" - Olive-Drab.com
5. "Technical Bulletin CW-6, Army Assault Gas Mask, E6-3-7, April 26, 1944"
6. "Report of Test: Assault Gas Masks, E6-3-7, Test Section; The Infantry Board, Fort Benning, Georgia, February 7, 1944"