That is not me; screen grabbed from Sportsman's Guide who's nice enough to demonstrate some gear. I figure to start with sleeping gear in this new sub-series for two reason: 1) in terms of history and options it is on the simpler side; 2) it's more than just a militia or field consideration but of general preparedness. I should know: we Texans still recall well the crippling winter of 2021 which exposed both an overreliance on the electric grid for survival and the consequences of not being ready to do without. And that was a once-in-a-century deep freeze for us; how much more important for those in more northern latitudes?
Now to be fair there are a great deal of valid options, some made in the USA. I will not look at those in a positive or negative light since I focus on US military issue for reasons stated previously. On that note, foreign military options in the surplus system can be just as good (particularly from countries with strong winter cycles of their own) but, while I would offer them due respect, the fact is I am not familiar enough with any of them to express authoritatively on how good they are.
WWII Origins
Centuries of bivouac logistics were as simple as could be for fielding large armies in enough comfort to get them to the fight. The pup tent (which may or may not offer adequate waterproofing) became such an entrenched standard the classic canvas shelter half remained basic issue for every soldier and marine until at least the 1980s. Shelters will be considered a separate topic and covered in a later post.
The blanket, the best field issue typically being made of wool, is the other classic part of the bivouac kit. Standard cold weather protocol through both world wars was merely to issue extra blankets and leave it to the troops to make best use of them. Adaptations such as foxhole shelters abounded enough to get on the books, and while it may have been the best available to field sufficiently for the number of troops deployed to Europe there was clearly room for improvement.
Among the developments of WWII was the proliferation of alpine fighting: the Axis had mountain troops so America matched that capability with formation of the 10th Mountain Division. It was not a so much a special force like the Ranger Regiment or British Special Air Service but its members were (and still are) a cut above, getting not just specially trained but specially equipped for freezing, high-altitude conditions. Along with their ski poles and snowshoes came a military adaptation of something that had successfully taken off in the civilian bushcraft realm: the sleeping bag.
The M-194X Series
This post will not delve into the scientific details of how US issue sleeping bags work nor the fine details of each build but focus on general development and design intent. Catalogued specifically for the 10th Mountain (though available in the system for others who could afford the surplus) was the initial M-1942 Mountain Sleeping Bag along with a water-repellant case (what would today be referred to as bivy cover) and carrying bag for hauling it in the rucksack (another special piece of gear for mountain troops). Also available was a two-bag extreme cold option called the Arctic Sleeping Bag, possibly in anticipation of fighting in Norway. Though not made available until the European Theater had already closed, each of these designs were refined into M-1945 with the same Mountain and Arctic nomenclature.
Details are scarce so this is stated under correction: while M-1942 was the initial result of successful tests what made M-1945 refined was common standardization of components. The M-1942 Arctic system was not compatible with pieces of M-1942 Mountain but M-1945 was what first made the Mountain Bag the inner layer of the Arctic assembly while making either compatible with the M-1945 bivy cover. This made for a modular system that could be carried and set up in any configuration depending on conditions, yet for the time being remained a special issue item for cold weather operations while the rest of the service kept getting their regular wool blankets.
The opening of the Cold War prompted a long push to advance beyond WWII by implementing new equipment standards for all the services which would culminate in a new general service weapon (M14), load bearing ensemble (M-1956), and standardization of a sleeping bag as general issue (M-1949). This transition was interrupted by the Korean War which taught valuable lessons about cold weather fighting and how equipment from the previous war may not be best for winning the next one. The M-1951 Cold Weather Uniform & Ensemble was part of the application of these lessons.
M-1949 was the pinnacle of this first generation of feather-filled military sleeping bags and the first to be made general issue (despite still being called Mountain & Arctic). A standard piece of the M-1956 load bearing ensemble included the infamous "spaghetti straps," a crude but effective design specifically for the M-1949 Mountain Sleeping Bag either with or without a new waterproof bag made for carrying it on the upper back (this Waterproof Clothing Bag bag is still issue today but used to keep other than just a sleeping bag dry). The Arctic ensemble was the same double-bag system as before except there being no new canvas bivy cover; both M-1949 bags are backwards compatible with the M-1945 cover but the lack of a successor here indicates a new philosophy taking hold in these developments.
Shielding From the Elements Almost as soon as the M-1949 system was approved there also came addressing the need for elemental protection in order to make the sleeping bags work as intended. Out in the field there are no cots (such as that pictured in the beginning of this post) which necessitates ground shielding. While alpine troops were trained to formed beds of boughs and other natural resources, regular troops needed something to more intuitively work for them. From the 1950s through early 1980s this protection took the form of a compact air mattress, essentially a military-issue variant of your guest floor bed (or water floater if you will) inflated by mouth. Apparently it was effective enough when it worked, but the feedback was not consistently positive since it was neither that easy to make work nor highly durable (obviously breach of an air bladder renders it ineffective) plus added considerably to carry weight. As the Cold War drew to a close this was replaced with a foam mat that, like the sleeping bags, had its rolling components attached which was a simple as it could get, and was much lighter and carried easier with all load bearing ensembles of the time. Though a self-inflating air mattress was produced for issue in the 90s and today the USMC prefers their own foam mat that folds rather than rolls, the now-classic rolling mat is so accessible and useful it should be considered essential bivouac gear for the militiaman.
The Single-Bag Solutions
While M-1949 remained standard for nearly 3 decades, the Vietnam War prompted a 180° turn from cold to hot weather ensembles; sleeping bag design went on the backburner for a while since even the basic Mountain was unnecessarily warm for most. What took charge instead was something that bridged the realms of sleep and shelter and remains a favorite today. In fact it was never even meant specifically for hot weather (and had to be modified to make such conditions more tolerable) but is still among the best pieces of equipment for not just warfighters but fieldcrafters in general.
Ponchos as rain protection with shelter-building capability had been used in WWII (primarily by Marines) but as part of their service-wide standardization in the 1950s were remade in waterproof nylon. Some of these heavyweight OG-207 originals remain available secondhand today and are the best complement to cold weather components, either the M-1951 (or succeeding M65) clothing ensemble or as the cover for one's sleeping bag. This is my theory not backed by official documentation I've found, but I believe the reason why bivy covers went away for a long time after M-1945 was because the sleeping bags were now meant to be used concurrently with field shelters, whether small-unit tents or individual poncho builds (now that a waterproof poncho was standard issue).
The 1970s was one of those times of cost-cutting and a greater military focus on "efficiency" that always reflects in equipment as well as personnel reductions. The venerable M-1949 Mountain Bag gave way to the synthetic build Intermediate Cold Weather Sleeping Bag; a heavier Extreme Cold Weather Sleeping bag succeeded the M-1949 Arctic ensemble. The design philosophy and overall shape (thus compatible with the still-standard pneumatic mattresses and waterproof carrying bags) was the same, the difference really only being material substance and that for extreme cold two bags was reduced to one. These sets remained standard through the 90s.
I have limited experience with these bags and in few conditions so much of this assessment is anecdotal research from various places on the internet. Being surplussed as successor systems took over standard issue in the 2000s kept M-1949, Intermediate and Extreme Cold bags highly affordable and desirable for some time. This remains so in relative terms only since (with exception of the now-collectible M-1949) all have experienced price increases but are still cheaper and easier to find available, sometimes unissued, secondhand.
Even though M-1949 Mountain and ICW bags are meant to operate in similar temperature range, as are M-1949 Arctic and ECW bags relative to each other, this is not necessarily the case. Remember that the key difference between both systems is M-1949 has a much higher natural material content while newer bags are synthetic. Temperature comfort is relative to the individual anyway but reports are consistent in these considerations: the ICW bag is desirable only in a very narrow temperature range between being warm enough for a ranger roll and cold enough to call for the ECW bag, and the ECW bag is noticeably less effective in frigid conditions than the feather-lofted M-1949 ensemble.
Ranger Roll: The Warm Weather Sleeping Bag The alpine sleeping bag systems were not the only ones made for American troops in WWII; even back then there were designs on a sleeping bag for general troop issue however, much like the M2 carbine, it was finalized too late and had to wait until Korea for wartime use. Referred to in some circles as M-1944 (after its year of contract) it had nothing to do with the M-194X series and was simply wool blanket sheet made into a closable sleeping bag form. It was light, simple, reportedly very comfortable for mild cold (especially if combined with a bivy cover or poncho), and a portent of things to come.
When the general issue poncho was produced in the 50s so was a synthetic poncho liner to go with it, a piece of kit troops fell so in love with it ultimately replaced the wool blanket for field use. A poncho can be a decent shelter (including warming layer) on its own, but designing it to combine with the liner thus forming an expedient sleeping bag for mild conditions was genius and remains standard today. Build a shelter overhead for the rain and wind, lay it atop a sleeping mat, and the lined poncho can be effective for emergency survival even in freezing temperatures (assuming proper cold weather clothing is being worn). Particularly here in Texas where it is warm much of the time I have given thought to more than one lined poncho assembly that I can roll up and wrap in several variations of load bearing gear (hence why this is called "ranger roll"). The secondhand supply of original OG-207 and M81 Woodland ponchos is drying up and unfortunately prices are raising accordingly in the 2020s. While several commercial vendors have stepped in to fill the void I have serious doubts about their build quality, not to mention the chance that commercial camouflage print is ineffective under night vision. While plenty of ponchos remain findable in US Army UCP and that is a good nighttime camouflage, do I really need to go into detail how terrible UCP is for daytime? OCP and MARPAT ponchos and/or tarps (also designed to work with poncho liners) may be more ideal but are also expensive due to being current issue and not many getting surplussed.
Enter the 21st Century Sleep System
Particularly when it comes to equipment there is a constant adage when it comes to the military: what is old is new again, especially in the 21st century United States Army (hello again, pinks and greens!). Just a few paragraphs ago it was established that the M-1945 (and mostly also its succeeding M-1949) system sleeping bag ensemble consisted of a single Mountain type, combined two-bag Arctic type, plus water-resistant cover compatible with either. Simplification of issued gear with the bags that replaced M-1949 only brought matters back into "room for improvement" territory.
In its earlier design days the Individual Integrated Fighting System (IIFS) was not envisioned as a total replacement for the standard ALICE load bearing ensemble but as an option to augment the capacity of specialized troops like 10th Mountain. Much of the criticism of IIFS is predicated on its comfort issues in hot weather which makes perfect sense considering it was originally designed for the cold. Again, this is technically my own theory as I cannot cite any official documentation to back me up on this but I offer as strong evidence the fact that the official IIFS manual from the late 1980s includes one unique set of gear not typically included grouped in with it (probably because it is the rarest component): the Extreme Cold Weather Sleep System or ECWSS.
I will save how ECWSS fits in with IIFS for when I post about load bearing gear, but for those aware of its existence it is a matter of interest due to how it first launched the design philosophy for the later general issue Modular Sleep System (much like how IIFS itself ended up being both the transition and inspiration for MOLLE). The Gore-Tex bivy cover is a very welcome addition over the uncovered ECW sleeping bag and the overall build, down to the included compression sack, is as good as it gets in this class. Though I happen to have one I mention it here more as historical reference because it is very difficult to find one today, especially including the unique sleep hood and booties. Note that despite similar overall design no ECWSS components are compatible with MSS or vice versa.
Which brings us to the Modular Sleep System (MSS), still Army issue today while the Marines have opted for their own similar 3 Season Sleep System (speaking of the Marines, in what may be a shout-out to the vintage wool sleeping bags the Corps also has what they call an All-Purpose Liner which is poncho liner materiel in zippable sleeping bag form). One in possession of a complete MSS may opt to carry just the lightweight Patrol Sleeping Bag, the heavier Intermediate Cold Weather Sleeping Bag (shares the name but differs from the 1970s variant it succeeds), Gore-Tex bivy cover for either, or combine both bags with the cover and stuff the whole assembly into the included compression sack should extreme cold be anticipated. Some have said the combined MSS assembly is less effective against cold than the single-bag ECWSS, but relative to the more available ECW sleeping bag on its own there should be no doubt MSS is a winner with major versatility bonus. If there are any issues they would be cost of a complete set (expect to pay at least $250 if still in good shape; it may be more cost-effective to acquire individual components, especially the bivy bag, separately) and that, like the older ICW sleeping bag, patrol and intermediate configurations are heavier to carry and somewhat overlap covering conditions for which a ranger roll would still work fine. Yet, like with so much equipment made for the military, it is no small quest to find better value for the money.
In Summary
I thought it best to illustrate the general points thereof with this little chart, plus to reference in summary which systems are designed for which conditions with official names in order to aid distinguishing them. Of course the primary dictating point is one's overall climate, but true preparation accounts for the total range of conditions in all four seasons even if that means some of this may be unpacked once or twice a year at most. Some cost considerations were mentioned earlier but now is the point to consider all else. The M-1949 Mountain Bag (not so much the Arctic Bag which is rarer and only effective combined with the Mountain Bag) is still out there but as they are older many may not be holding up that well; if a good one can be found the M-1945 bivy cover is also findable and makes a perfect complement although its waterproofing might need restoration. For a cold shelter-in-place emergency (like one of those nasty ice storms) the ICW bag is still easily-found and not that expensive...it just isn't that effective thus use under frigid inclement conditions outside is not recommended. Its contemporary ECW bag is also easy to see available but as they have pretty much become impossible to find for under 3 figures this is something extra to go for only if in your own weighted judgment it would be worthwhile.
The ECWSS and MSS are cream-of-the-crop but the former is rare while the latter is expensive. I would only consider either of these if anticipating having to bivouac outdoors in the cold because that calls for special protections these ensembles come with out-of-the-box (so long as they are complete and used properly). Otherwise any of the older systems mentioned above are a good start, and any cold weather sleep system should be complemented with cold weather clothing anyway. There is nothing wrong with extra blankets and huddling together either, as was done by soldiers before the 20th century.