The Rhine Raids were a series of raids along the Rhine River. While numerous small settlements were sacked, large cities such as Cologne and Utrecht were sacked by the Danes and the Swedes. The raids continued until the Byzantine Empire intervened in the war in 849 and subsequently removed the Danes from the Rhine in 851.
Following the expulsion of Frankish forces in Jutland, the Vikings were quick to retaliate. An invasion force set out into Frankish territory from Jutland on foot while the Swedes and Danes began to break through the Frankish naval grid at the Rhine. In 848, the Vikings broke through in the Frisian area, taking the immediate area and sending ships down the Rhine River to attack various settlements and cities.
Raid of Utrecht
As Danish forces attacked the Franks in Saxony, the Swedes joined the war against Francia in full. They began sending ships into the Rhine river. The initial raids were relatively small; fishing boats were destroyed and towns were sacked. The attacks became more aggressive in the spring of 848 when Utrecht was attacked by the Swedes and the Danes. Unlike the Raid of Paris, this attack was a confirmed massacre. According to some sources, the Rhine ran red.
The Vikings did not leave with a ransom; they simply moved on when they felt it necessary.
Raid of Cologne
The next major attack took place in September of 848. Cologne was attacked by the Swedes and the Danes. A massive fire engulfed the northern portions of the town, resulting in the Great Fire of Cologne. The Vikings are said to have gone into burning buildings for anything of value. Following the raid of Cologne, the Vikings disappeared once again down the Rhine River.
First Battle of Aachen
After the battle of Cologne, the Vikings sent ships down the Meuss River to attack the Frankish seat of power, Aachen. This battle, unlike the raids of Cologne and Utrecht, would end in the occupation of the city rather than the simple devastation. Aachen was severely damaged in the attack, resulting in the destruction of many buildings, including much of the Palace of Aachen. In the romanticized history of the battle, Fire on Water, which was the accepted account of the battle until the 20th century, Lothair I valiantly fought against Ragnar Lodbrok before being struck down. Recent evidence, however, has pointed to Lothair being killed when the Palace of Aachen collapsed.
Second Battle of Aachen
The Second Battle of Aachen, led by Atticus I himself, allowed Frankish forces to retake the city. The area surrounding the ruins of the Palace of Aachen was highly guarded, not to mention strewn with rubble and debris from the First Battle of Aachen. Atticus' forces surrounded Wurm. Several skirmishes outside the city resulted in the Vikings pulling back to the city of Aachen, waiting for the Frankish and Byzantine forces to reach Aachen. Siege engines from Bonn arrived on the third day of the battle, allowing the Frankish and Byzantine forces to enter the city and retake it, forcing the Vikings to either retreat down the Wurm and up the Meuss River or face death.
Sack of Verdun
As it turned out, the Vikings occupied Aachen to draw attention away from their next target, Verdun. The town was sacked, gold was taken, and people were slaughtered. While this tragedy was costly, it marked the end of the Rhine Raids. The Franks were able to ambush the force at Liége.
The Rhine Raids resulted in the destruction of many lives and towns. Settlements were left abandoned following Viking raids, leading to a localized food shortage immediately following the attacks. The population of the Rhine settlements was lowered by as much as 10% due to deaths and people fleeing the area during the raids. Following the attacks, as much as 20% of the people that had survived the attacks had left the Rhine area. The population of the Rhine settlements did not recover for another century.
The death of Lothair resulted in Atticus I's crowning as the Frankish Emperor, a then-controversial move. The raids are now seen as the battle that ultimately forced the Franks into abandoning many self-destructive traditions regarding assumption of the crown following the death of an emperor.