They plundered and occupied the city, withdrawing after Charles the Bald paid a ransom of 7,000 French livres [2,570 kg (83,000 ozt)] in gold and silver.

[9] Reginherus's Vikings raided Rouen on their way up the Seine in 845,[8] and in response to the invasion, Charles—who was determined not to let the royal Abbey of Saint-Denis (near Paris) be destroyed[8]—assembled an army which he divided into two parts, one for each side of the river.

[10] The Franks could not assemble an effective defence,[5] and the Vikings withdrew only after being paid a ransom of 7,000 livres (French pounds) of silver and gold by Charles the Bald,[9] amounting to approximately 2,570 kg (5,670 lb).

[12] While agreeing to withdraw from Paris, the Viking army pillaged several sites along the coast on the return voyage, including the Abbey of Saint Bertin.

[8] Although Charles had been criticised severely for granting the large ransom payment to the Vikings, he had other more critical issues to deal with at the same time, including disputes with his brothers, regional revolts and disgruntled nobles, as well as pressure from abroad.

[12] The same year, a Viking fleet sacked Hamburg,[3][5] which had been elevated to an archbishopric by Pope Gregory IV in 831 on the initiative of Louis the Pious to oversee the Saxon territory and to support the introduction of Christianity to Scandinavia.

Horik eventually agreed to the terms and requested a peace treaty with Louis, while also promising to return the treasure and captives from the raid.

[13] While Ragnar showed the gold and silver he had acquired to Horik and boasted about how easy he thought the conquest of Paris had been,[9] he reportedly collapsed crying while relating that the only resistance he had met was from the long deceased saint.