Northmen: The Viking Saga AD 793-1241 by John Haywood

in Viking activity when a Danish army occupied the Isle of Thanet in Kent and settled down to spend the winter there in a fortified camp. So far raiding had been a seasonal activity, confined to the summer months, and by September the Vikings were heading home to avoid getting caught at sea by autumn gales. By wintering in their victims’ territory, Vikings could extend the raiding season into the autumn and make an earlier start the following spring. Spring 851 saw the arrival of a new Viking fleet in Kent. Reported to be 350 ships strong, this was by far the largest Viking fleet to attack England so far. This formidable force sacked Canterbury, England’s premier ecclesiastical centre, and then the growing port of London. Mercia’s king Beorhtwulf brought the Vikings to battle but was heavily defeated. Buoyed by their success, the Vikings crossed the Thames and invaded Wessex, only to be defeated in battle at the unidentified location of Aclea (‘Oak Field’). It was the greatest slaughter of heathen raiders the Anglo-Saxon chronicler had ever heard of.
    In the same year Æthelstan, a son of King Æthelwulf of Wessex, defeated a Viking fleet in a naval battle at Sandwich harbour and captured nine ships. Naval battles were exceptionally rare in the Viking Age. Ships of the period could not remain at sea for extended periods to patrol for enemy fleets so the chances of intercepting a Viking fleet on the open sea was negligible. Naval battles, when they did occur, usually took place when one fleet managed to trap another in a harbour or estuary, as Æthelstan’s seems to have done here. These victories bought England only a year’s respite and in 853 the Vikings were back on the Isle of Thanet. Yet despite the unrelenting raids, Æthelwulf of Wessex felt that his kingdom was secure enough for him to go on a year-long journey to Rome to visit the pope in 855, taking with him his favourite youngest son, Alfred. The Vikings were a severe nuisance but they were not, so far, seen as an existential threat.
    The Viking way of war
    After more than half a century of Viking raids, the Anglo-Saxons appeared to be meeting the Viking challenge. True, many important towns had been sacked but they would certainly have been well aware of how much more severely Ireland and the Frankish Empire were suffering at the Vikings’ hands. The Anglo-Saxons had never run away from a fight and when they had brought the Vikings to battle they had won more often than they had lost. Despite their ferocious reputation, Vikings were not invincible military supermen. Their weapons were no better than those of the Anglo-Saxons or Franks and nor did they use innovative battle tactics. On a battlefield it would have been hard to tell the Anglo-Saxons and Vikings apart. Both fought on foot and relied on the shield and spear as their main weapons, and both formed up for battle in a linear formation known as the shield wall, in which each warrior stood in rank with his shield slightly overlapping that of the man next to him. Depending on the size of the army, the formation could be several ranks deep, with the men in the rear ranks adding weight to the formation when it came to the pushing and shoving when battle was joined, and stepping forward to fill the front rank when men were cut down. It was essential to maintain the integrity of the shield wall. The critical point of many battles came when one side began to lose its nerve and tried to withdraw. If the shield wall remained intact the defeated army could withdraw in good order to lick its wounds without suffering heavy casualties. If the shield wall collapsed it was every man for himself and casualties would be heavy because the victors could strike the exposed backs of their fleeing enemies.
    The real secret to the Vikings’ success was their mobility, which meant that they, rather than the defenders, usually held the initiative. In pre-modern times, travel by water was always faster than travel by