NOTES ON THE SWISS ARMY HELMET MODEL M18 (1918)
Sizing Data
Note: The original series of Swiss M18 Army helmets were manufactured (of Manganese Steel alloy) in only two sizes, both of which featured an internal circular head suspension that was slightly adjustable, through the use of a draw string drawing together the three leather sizing pads. The first size (identified by a printed ‘A’ on the rear inner shell) identified that size suitable for heads smaller than 58 cm. The second size (characterised by a printed ‘B’ character) identified the size intended for 59 cm and larger heads.
The size cipher was usually superimposed over the printed production serial number of the helmet and on earlier helmets was printed in letters on the rear inner shell; although it has not been confirmed yet, later iterations had the size character stamped into the underside of one of the sizing pad leather straps. A total of roughly 600,000+ of these helmets (or all iterations) were produced, from 1918 through the last year of production (1971), when the newer M71 helmet was introduced to replace the M18 types.
When the 1940 iteration of this helmet was produced (designated the M18/40), a newer ‘horseshoe-shaped’ (3/4th of a circle) internal head suspension sling of similar construction to the previous circular version was introduced that permitted a much wide range of size adjustment. Consequently, it would seem that only a single steel shell was manufactured that accommodated both smaller and larger heads (a ‘one-size-fits-most’ concept), although this surmise has not yet been evidentially documented and remains a hypothetical surmise at this time.
It is useful to note also that the typical European head is somewhat rounder than average, elsewhere in the world, and I presume that ‘smaller’ head sizes predominate over larger heads throughout Europe, given the large number of smaller military caps and other types of miitary headgear that one finds as surplus (and a consequent paucity of larger sizes) in smaller sizes. It would be interesting and illuminating, I’m sure, to see actual international anthropomorphic/ergonometric data bases on this matter, but such research is beyond the scope of my intent to pursue here.
The M18/40 (iteration) helmets I have come across have no such sizing identification printed on them, apparently for the above reasons, although the early M18 helmet sizing identifications were merely printed on the internal shell and may well wear off over time, given use (see subsequent notes about sizing ID possibly being embossed or printed on underside of the leather head suspension sling straps).
M18 type helmets used by Swiss Rescue/Emergency/firefighters, are distinguished by bright ‘fluorescent’ yellow paint. On these special helmets (all of the M18/40 or newer types), a ‘P’ ('Police') or 'F' (Fire) character is often noted above a serial number on the rear internal shell. However, other evidence suggests that a certain number of the regular Manganese Steel M18s Army helmets were called up, refurbished and also painted the Emergency/Civil Defense Services yellow. Examples may be encountered these days on eBay, but are not as keenly sought after as the combat models (for unknown reasons).
The earliest M18 helmets featured a broader and wider ‘skirt’ than did the later versions, which had shorter, somewhat more abbreviated skirts. Apparently, it was noted that the broader, wider skirt aspect of the early helmet made sighting and shooting a rifle somewhat problematic and notes of that period state that Swiss riflemen often had to wear the helmet reversed in order to sight and use a rifle accurately in combat situations. There are several photographs that demonstrate this effect, showing how in a prone position a rifleman’s helmet would probably be pushed upward (thereby pushing the forward part of the helmet’s visor-skirt downward, obscuring vision) as he attempts to aim a rifle or similar long handheld weapon in that position. Of interest here is the fact that the German Imperial Army troops seem to have had no similar reports of difficulties with their M16/18 type ‘coal scuttle’ Stahlhelms in the First World War (1WK), despite their having a similar low-reaching helmet skirt in their rear aspect.
Interestingly, existing documentation suggests that the Swiss M18 type helmet was adopted by several other nations in addition to the Swiss Army.
The Swiss Model M18/43 Iteration
The original M18 helmet had a smooth external finish that was a dull gray-green in color, but this could prove a liability in wet concealment situations, since the gray-green paint, once wet (or worn smooth), would become quite shiny and reflected light, thereby revealing the wearer’s position. In 1943, the earlier produced M18 helmets used by combat troops were recalled and the exterior repainted with a dark anthracite paint mixed with very fine sawdust particles to produce a variegated texture, non-reflective exterior surface (a technique resources suggest was borrowed from the American experimental helmet studies). This iteration was designated the M18/43 standard.
All new helmets produced thereafter featured this finish applied at the factory. The relative wear of a helmet thus treated may be gauged by the condition of this finish. The more user-wear experienced by the helmet, the less perfect is the finish, with areas of obvious wear and spots (particularly along the rim) where the finish has worn off entirely to reveal the bare metal. Helmets with this exterior finish almost completely intact are seldom found, due to the fact that by the time they were eventually released by the Swiss Government for surplus sale, they were considerably and substantially well-worn!
As of the year 2021, retail prices for used Swiss M18 helmets of all date-of-production iterations (M18, M18/40, M18/63, etc.) may vary considerably (between US$40 and US$ 140 or so, depending upon overall condition), but it is inarguable that whereas a few years ago there seemed to be rather plentiful numbers of these helmets on the collector market, by the present date (mid-2021), available stocks released by the Swiss Government seem to have notably dried up (despite over 600,000 units having been produced). The result is now that specimens are generally a bit hard to source out now, and in particular very good-to-excellent specimens (along with the ‘B’ larger size shell types) are extremely difficult and sometimes almost impossible to find offered for private sale. [The LRG "B" size in good condition is usually well-worth several times the listed value of a smaller (and much more common) "A" helmet.]
Those M18s that one does find on offer via eBay or other venues are generally put up for sale with very little descriptive information other than a very basic ‘M18 type Swiss Helmet’ identifier. Most private retail (as well as commercial) sellers have absolutely no idea what size helmet their item is and efforts to inquire as to that are almost inevitably futile. This is complicated by both the fact that the Swiss M18 sizing code in not generally understood or known 
Design Inspirations for the Swiss Model M18 Army Helmet
As a point of interest, the US Army experimented with a number of protective helmet designs in the early days of WW1 (1917). This program was carried out under the aegis of Dr. (Major) Bashford Dean of Columbia University, who was appointed by General John Pershing to investigate the possibilities of developing a suitable American Army protective helmet suitable for trench warfare. A series of helmet designs ensued, and among them was a ‘US Army Experimental Model 5 Protective Helmet’ which was evaluated and ultimately rejected by the US Army. However, it bears a striking and startling similarity to the original Swiss M18 helmet (as did several of the earlier American designs); a comparison of the two respective national specimens, side by side, is an eye-catching demonstration of how remarkably similar they were to each other. Whether or not the Swiss took note of the US Army Model-5 helmet in 1917 when they designed their own M18 helmet has never been clearly established or disproven, but it is almost impossible to dismiss this distinct possibility and the circumstantial evidence strongly supports that likelihood!
When one attempts to read between the lines of Dr. Dean’s 1920 book titled Helmet and Body Armor in Modern Warfare (Yale University Press), the remark is made that some of the American experiments in helmet design were ‘shared with colleagues in France’ (who in all likelihood shared them with other Allied or neutral European confreres). That almost seems like a very discrete and indirect way of saying that data and information was shared unrestrictedly. Although Dean states explicitly in his book that the US Army M5 and M8 helmets were developed independently of the Swiss helmet efforts, the similarities between the Swiss M18 and the American counterparts are all too remarkable to dismiss this possibility categorically!
An extremely helpful paper on the subject of those early American Army helmet designs has been prepared by Peter Suciu, which may be found at the following URL: https://www.militarytrader.com/militaria-collectibles/american-experimental-helmets-from-wwi. Another useful article on the US Army Experimental Model 8 Helmet (which appears similar to the Model 5 helmet, except with an additional protective frontal visor attached to it) may be found here: https://collegehillarsenal.com/experimental-us-8-helmet-very-fine-very-rare.
One final note
The internal head-suspension sling that is used in the Swiss M18 army helmet is further remarkably similar to that used in Maj. (PhD) Bashford Dean’s experimental helmet #5…more supportive evidence that Switzerland adopted the US Army Experiment Helmet #5 as its archetypal inspiration. This suspension system consists of a circular head-sling to which are attached three leather cushioning pads that, along with a drawstring gathering cord, permits a certain rude amount of individual custom sizing. A similar system is also noted in use in the ubiquitous German M16 ‘coal scuttle’ helmet (Stahlhelm), which suggests that the various nations were keenly following each other’s developments in battlefield helmet design studies; it is uncertain as to who copied whom in most cases, but it is fairly obvious that there was an appreciable amount of ‘international design-feature sharings going on between the Allied nations, in the earlier stages of the war.
Summary
This does not presume or pretend to be anywhere near a complete assessment of this endlessly fascinating Swiss helmet. It is intended merely to provide a rudimentary gathering together of some of the more salient points focused on that item. There are undoubtedly some inaccuracies contained herein and input that reflects more accurate data would be greatly appreciated. Please feel free to contact me in that regard! Thank you.
What do you make of this with the red numbers and no letter above? Also the smooth gray finish has me curious.
