Wearing maille armour on its own has a limited protective effect. While the metal mesh will limit the cutting force of a sword or an axe, it will have much less effect against the sharp point of an arrow or spear-tip; the only way to spread the impact of a blow is some sort of padding. By the twelfth century the padded gambeson or akheton was in widespread use, but exactly how this padding effect was achieved in the period the Society covers is a source of debate.
Rather frustratingly, there is no direct evidence for padding being worn underneath maille armour in Viking age England or Scandinavia. This does not mean it was not used - but there is no evidence to suggest that dedicated padded armours were in use. It is entirely possible that warriors wore a couple of thick woollen tunics, providing a degree of cushioning without needing any special equipment or leaving any sort of evidence behind.
For most of the period we cover, early medieval depictions show warriors or combatants either wearing no body armour or a short sleeved and waist/mid-thigh length maille shirt (haubergeon). If padding was worn, it’s most likely to have been in the form of one or more woollen tunics and not dedicated padding like the later gambeson/akheton.
Evidence for under-armour padding in the twelfth century
Dedicated padded armours (i.e. a padded gambeson/akheton) were certainly in use in the twelfth century and beyond – there are plenty of literary references, depictions and even a few surviving examples (e.g. the Black Prince’s under-armour in Canterbury cathedral). For example, the Assize of Henry II (1181) specifies that a free man with moveable property worth more than 16 marks should maintain a "aubergel" (mail shirt) but a burgess (poorer) should maintain a "wambais" (gambeson) instead.
The memoirs of Usamah ibn-Munqid (a twelfth-century Syrian warrior-noble who spent much of life in the entourage of Saladin) recalls an incident from his youth in the Syrian town of Shayazar, where a small group of Frankish knights were defeated. The knights' armour was bristling with arrows and at least one was pulled from his horse in a flurry of blows from an infantry mob - but they still survived to be ransomed.
This is also the period where we read of knights 'sleeping upon their armour', which makes more sense if the 'armour' is a thickly padded or quilted gambeson rather than a maille shirt.
Frustratingly this type of padded under-armour just appears in western Europe, without clear evidence of how and when it came into use.
A context for the introduction of dedicated under-armour padding
Maille armour seems to have changed significantly in the eleventh century. Depictions regularly show longer maille hauberks, i.e. wrist- and knee-length, and often with a band of some form at the cuffs and hem. The Bayeux Tapestry is one of the most obvious examples, but similar features appear in carvings and manuscripts from across late eleventh and early twelfth century Europe (including a fragmentary stone carving from Winchester, dated to c.1050).
This longer armour seems to have been adopted in mainland Europe before reaching England – it is found in Continental manuscripts from around 1000 onwards, though English manuscripts from the early 1000s still show the shorter hauberk. The eleventh century seems the most plausible context for the period where padded under-armour came into widespread use, alongside longer maille shirts.
It is worth noting that dedicated under-armour padding had remained in continuous use in the Byzantine and Islamic world, where it had continued in use since Roman times. This is borne out by the terminology used. ‘Akheton’ derives from the Arabic ‘al-qutun’, meaning ‘cotton’; ‘gambeson/wambeson’ may come from the Greek ‘bambukon’ or perhaps ‘kavadion’.
The period of the Crusades seems an obvious point for western military men to have large-scale exposure to padded armour, see the benefit of it and encourage all their friends to use it. However, there was a reasonable amount of contact between west and east through the eleventh century, and it is quite possible that the idea was adopted earlier.
Under-armour padding in the Vikings Society