The Australian Army issued a multipart sleep system to its troops during much of the Vietnam war. Unlike a sleeping bag, this set consisted of a number of different parts that fastened together to offer a range of protection depending on the weather, together with an inflatable mattress designed to offer some comfort on a hard floor. I was lucky enough to pick up a large selection of parts of this sleep system some months back:

The base of the sleep system was the mattress, made up of three inflatable sections, each with three tubes in them. These inflatable sections are made of a heavy duty black plastic:

These sections each have a valve to allow the user to inflate them, usually by simply blowing with his mouth as on a child’s inflatable beach toy. The valves are marked with the /|\ mark and a date, here 1965:

Once inflated the tubes were fed into a special mattress cover with three pockets:

This cover is about six feet long and made of a green waterproof fabric:

The pocket at the end is to allow an inflatable pillow to be added, although by all accounts few soldiers ever saw this part of the system. Once the inflatable sections have been added, the flap at the bottom is folded over and secured with press studs:

This cover dates from 1966:

One former soldier recalls the inflatable mattress and its cover:

I am yet to meet anyone that had more than one night’s successful sleep without one or more of the inflatable inners going down, and not in a good way;-). When I was issued mine, I discovered they had all been slashed to save me carrying them on patrol without them being usable! The real benefit of the ‘mattress’ is one key feature and that is the reason I still carry one, albeit it slightly modified. Each corner has a reinforced loop for stretcher poles to be passed through. Mods? Carefully unstitch the seams that create the pockets for the bladders. You now have a ground sheet or top sheet, improvised sleeping bag almost as efficient as the horse blanket combo! Improvised stretcher, with or without poles. I whipped this out the other weekend on a mass casualty Exercise to save our back evacuating the casualty.

Another soldier agrees about the leaking tubes:

It’s always one of the side tubes that leaks leaving you with a narrow mattress, not the middle one

Another common use for the inflatable mattress was as a cover for linked ammunition, the ends being cut off one of the tubes and the ammunition passed through to keep moisture and dirt off it (although care had to be taken that water did not condense inside the tubes and create the problem you were trying to avoid).

The mattress was usually dumped as being a waste of space, however the other parts of the sleep system were used more often. These consisted of a large brown woolen blanket with loops that was generally called a ‘horse blanket’ by the troops:

Again this blanket has a helpful label sewn to it dating it to 1966:

The loops were used to hold the blanket inside a nylon outer, known as a ‘silk’. This was a green bag that acted as a semi-waterproof outer layer and helped keep the heat inside the sleep system:

The final part of the system was the waterproof ground sheet, commonly known as a ‘hootchie’ made of a heavy green nylon:

This is fitted with loops and press studs to allow it to be used as a basha or wrapped around the rest of the sleep system to waterproof it:

It is fair to say that the sleep system was not popular, and many soldiers just carried the silk into the field:

The term “silk” came about from a discussion with a Vietnam Veteran a while ago – he used the bag as a standalone jungle sleeping bag on operations and he called it a “Silk”. I asked him about the sleep system and he’d never heard of it being used apart from the “Silk”. My old man is a Vietnam Infantry Vet and he had no idea – he remembers them and the blankets being issued at Kapooka, but not how they were used. In Vietnam he used an American poncho liner.

Another researcher explains further:

I interviewed some Vietnam veterans some years ago and discussed the sleeping arrangements when on patrol. They universally agreed that they slept wrapped in “Their silks” which was the sleeping bag liner. Not inside it just wrapped around them to keep most of the rain off and keep warm. If you had to make a run for it at night you tossed it and went. Not much of a loss and easy to carry.