Like the rest of early medieval warfare in western Europe, Viking warfare could not simply ignore the encumbering effects of winter on campaigning and logistics. As such, it was generally a seasonal affair, with a built-in winter holiday initially back home in Scandinavia but increasingly in overwintering bases and settlements once they popped up in Viking-held territories abroad. From such settlements the Vikings could participate in local politics, tactfully choosing sides, reaching agreements with their enemies, securing the payment of tribute, and launching new campaigns.

Even when it comes to inland battles, the Vikings' beloved ships remained crucial wherever they could be put to use. The ships had a shallow enough draught to paddle up the larger rivers, carrying anything from men to supplies and loot, meaning that whenever the Vikings campaigned near areas their ships could reach they had no need for annoyingly slow overland baggage trains.

Things get hazier, however, regarding the actual specifics of Viking combat in battles:

We know little of specific battle tactics. Those references that we do have suggest that the shield-wall was the most common tactical formation. Archery was probably also used to break up the shield-wall, as it was not an ideal position in which to receive arrows (it provided a large target, with little manoeuvrability), and the longbows known to have existed in this period would have penetrated shields and armour, though not necessarily deeply. (Williams, 28).

Horses, although used for their mobility, were probably dismounted for battle. Battle standards were carried near the leader or leaders, probably to indicate status. Some of these standards depicted ravens, such as the one used by Harald Hardrada at Stamford Bridge (1066 CE) against the Anglo-Saxons. Although shouting matches may have sufficed regarding communication in smaller skirmishes, one can of course only shout so loudly; animal horns may also have been used to bellow out signals and pick up the slack. For conveying more articulate orders and information, it is likely messengers would have zoomed across the battlefield at high speed.

One Viking force where such communicative measures would have been invaluable is that of the Danish 'great army' that razed havoc across England from 865 CE on, campaigning for years and bringing the kingdoms of East Anglia and Northumbria as well as most of Mercia to their knees. Even Wessex, under its leader King Alfred (r. 871-99 CE), struggled to resist the Viking forces but eventually won a decisive victory. The Vikings' great army disbanded c. 880 CE, its warbands seemingly jumping to take advantage of a succession struggle in the Kingdom of the Franks where they were active between 879-891 CE. Flexibility and keen opportunism were key.

Organisation

A large army would have been composed of several warbands, although we only know little about the precise organisation or command structure. Local kings, earls, and chieftains may all have led individual portions of the army, holding specific command roles and probably following some sort of hierarchic order. At the Battle of Ashdown (871 CE) where King Alfred beat the great Danish army, one of the Danish wings was led by two kings while the other was captained by 'many jarls' (Williams, 19), for example. As the Scandinavian kingdoms began to take on more unified shapes, bigwig kings such as the Danish King Sweyn Forkbeard (r. 986-1014 CE) were probably responsible for a more tightly-knit hierarchy, in which they themselves commanded the crews of several ships, supplemented by their main chieftains' personal forces. The total numbers of warriors then easily reached into the thousands in time of conflict.

Connections between the various kinds of leaders, and between them and their crews, could have taken the shape of kinship or personal ties, social ties, or could be loot- or tribute-driven. There probably was no such thing as a systematic levy for Viking fleets. Although the term leiðangr indicated a force directly under control of the king (and in this capacity it may have sporadically been used during the Viking Age), the specific levy connection is only known from sources dating to the mid-12th century CE and beyond. Instead, Viking Age ventures were likely mainly private affairs.

Harald Hardrada, Battle of Fulford GateMathew Paris (Public Domain)

It has been argued that the units in battle could have had their origins in the crews of ships, which sounds logical enough considering the Vikings' heavy reliance on ships and the sense of companionship that would have grown from helping each other deal with the occasional seasickness. As for the raiders and warriors themselves, they were generally young men – as per both the sagas and the skeletal remains that have been found. None of these as of yet definitively prove the existence of female Viking warriors. One can imagine more experienced warriors being invaluable, too, though, bringing some stability and knowledge with them. Indeed, accounts detailing the Vikings' years-long campaigns in the late 9th century CE paint a picture of adolescents or young adults joining up and remaining active into their thirties and even beyond. Interestingly, evidence has shown that troops may also have been partially drawn from areas outside of Scandinavia; a southern Baltic connection is attested to with regard to garrisons in Denmark, and even the Scandinavian forces active in England in the 10th century CE were a mishmash rather than reflecting any kind of 'national' army.