The Battle of Leuven, also called the Battle of the River Dyle, was fought in September 891 between East Francia and the Vikings. The existence of this battle is known through several different chronicles, including the Annales Fuldenses and the Anglo-Saxon Chronicle. The Battle of the Dyle occurred near the present-day location of the city of Leuven in Belgium. In the 880s the Vikings established a camp there that they used as a base of operations from which to launch raids into the fractured Frankish kingdom. Efforts to verify the report of the battle from the Annales Fuldenses, specifically the huge loss of life on the Viking side, have been hindered by the lack of archaeological excavations in Belgium.
Background
There is some debate about the catalyst for the renewed Viking assault on the continent more generally and East Francia specifically at the end of the 9th century. According to the Chronicon of Regino of Prüm, the Vikings were forced to abandon their assault on Britain, which they had been attacking at least since the 8th century. Here the Vikings particularly focused their attention on Ireland, and once they established their presence there they began launching raids into neighboring England and across the channel into Europe. The Viking raids continued throughout much of Europe for much of the next couple of centuries. In 866, the Danish ‘great army’ began a major assault on England, whose fractured kingdoms were initially easy targets. They quickly took over East Anglia, Northumbria, and Mercia, but the king of the West Saxons, Alfred the Great, slowed their advance. In 878, at the Battle of Edington, Alfred defeated a prominent Danish leader, and the main force of Vikings moved from England to the continent where they continued raiding all over, even besieging the city of Paris in 885–886. Charlemagne's great-grandson, Charles the Fat, paid them a ransom of silver and sent them off to Burgundy where they continued raiding and plundering, even sacking the abbey of Luxeuil.
Regino's Chronicon certainly reinforces this image, stating that after two decisive defeats in Britain, the Vikings moved their forces across the channel and began raiding and plundering the continent with renewed vigor. Simon Coupland and Janet Nelson suggest that the defeat in England coupled with the unique conditions in Francia in the mid to late 9th century made that part of Europe a prime target for the Vikings. Louis the Stammerer died in April 879, leaving to his two young sons a kingdom that quickly erupted in turmoil. Frankish nobles supported differing contenders for the throne, and their internal divisions left them vulnerable to attacks across the channel from the migrating and opportunistic Danes, who took advantage of the situation. Whatever the reasons, it is clear that the battle took place during a period of renewed and concentrated raiding by the Vikings on the European continent, centered on the fracturing Carolingian Empire.
The lead-up to the battle occurred during the summer of 891. While King Arnulf was off on the Bavarian frontier dealing with the Slavs, the Vikings met a Frankish force in battle on 26 June. The Franks were initially unsure about what their opponents’ aims were: would the Vikings make next for Cologne, head for Trier, or would they flee when they heard that a Frankish army had assembled to meet them in battle? The Franks eventually marched out and drew up in battle lines after crossing a stream called the Geule, then began discussing forming parties to scout their enemy. In the midst of these discussions the Vikings’ scouts happened upon the Franks. The Frankish army pursued the scouts without waiting for instruction from their leaders and eventually ran into the assembled Viking infantry in a nearby village, which easily repelled the disorganized Frankish attackers. Once their cavalry had been drawn to the battle, the Vikings easily defeated the Franks, who retreated, only to be cut down by their Viking pursuers. The Vikings then proceeded to raid and plunder, taking their captured booty back to their ships.
Part of King Arnulf's motivation for going to battle against the Vikings, according to Regino, was to seek revenge for his fallen men and to restore the image of the Franks, which had been severely damaged by their flight during the battle. Therefore, he assembled a substantial number of men and went to meet the Vikings in battle at the Dyle River, where the Danes were entrenched.