A 5,000 strong fleet of Danish Vikings invaded Frankish lands in 845 and only retreated after besieging Paris and securing a ransom from the Frankish King Charles the Bald. They were part of a series of devastating raids begun by the Vikings from the 790s.
The Vikings were led by a man named "Reginherus" or Ragnar, sometimes linked to the legendary saga figure Ragnar Lodbrok. The Vikings easily overcame defences set in place by Charlemagne and are known to have attacked the Abbey of Saint-Germain-des-Prés just outside the city.
Although struck by an outbreak of plague the Vikings overcame this to return home with their ransom of 7,000 French livres of gold and silver.
- 0845-03-29 Paris is sacked by Viking raiders, probably under Ragnar Lodbrok, who collects a huge ransom in exchange for leaving