Siege of Paris (845)

The Siege of Paris and the Sack of Paris of 845 was the culmination of a Viking invasion of the kingdom of the West Franks. The Viking forces were led by a Danish chieftain named "Reginherus", or Ragnar, who traditionally has been identified with the legendary saga character Ragnar Lodbrok. Ragnar's fleet of 120 Viking ships, containing thousands of men, entered the Seine in March and proceeded sailing up the river. The West Frankish king Charles the Bald assembled a smaller army in response, but as the Vikings defeated one division, comprising half of the army, the remaining forces retreated. The Vikings reached Paris at the end of the month, during Easter. After plundering and occupying the city, the Vikings finally withdrew after receiving a ransom payment of 7,000 French livres, or pounds (2570 kg) of silver and gold from Charles the Bald.

Background
The Frankish Empire was first attacked by Viking raiders in 799 (six years after the earliest known Viking attack, at Lindisfarne, England), which eventually led Charlemagne to create a coastal defence system along the northern coast in 810. The defence system successfully repulsed a Viking attack at the mouth of the Seine in 820 (after Charlemagne's death), but failed to hold against renewed attacks of Danish Vikings in Frisia and Dorestad in 834. The attacks in 820 and 834 were unrelated and relatively minor, and more systematic raiding did not begin until the mid-830s, with the activity alternating between both sides of the English Channel. Viking raids were often part of struggles among Scandinavian nobility for power and status, and like other nations adjacent to the Franks, the Danes were well-informed about the political situation in Francia; in the 830s and early 840s they took advantage of the Frankish civil wars. Major raids took place in Antwerp and Noirmoutier in 836, in Rouen (on the Seine) in 841, and in Quentovic and Nantes in 842.

Invasion and siege
In March 845, a fleet of 120 Danish Viking ships containing more than 5,000 men entered the Seine under the command of a Danish chieftain named "Reginherus", or Ragnar. This Ragnar has often been tentatively identified with the legendary saga figure Ragnar Lodbrok, but the historicity of the latter remains a disputed issue among historians. In or around 841, Ragnar had been awarded land in Turholt, Frisia by Charles the Bald, but he eventually lost the land as well as the favour of the king. Ragnar's Vikings raided Rouen on their way up the Seine in 845, and in response to the invasion, determined not to let the royal Abbey of Saint-Denis (near Paris) be destroyed, Charles assembled an army which he divided into two parts, one for each side of the river. Ragnar attacked and defeated one of the divisions of the smaller Frankish army, and took 111 of their men as prisoners and hanged them on an island on the Seine. This was done to honor the Norse god Odin, as well as to incite terror in the remaining Frankish forces.

The Vikings finally arrived in Paris on either Easter Sunday, 28 March, or Easter Day, 29 March, entered the city and plundered it. During the siege, a plague broke out in their camp. The Norse had been exposed to the Christian religion, and after first praying to the Norse gods, they undertook a fast, acting on the advice of one of their Christian prisoners, and the plague subsided. The Franks could not assemble any effective defence against the invaders, and the Vikings withdrew only after being paid a ransom of 7,000 livres (French pounds) of silver and gold by Charles the Bald, amounting to approximately 2570 kg. Considering Ragnar's earlier loss of land by Charles, the substantial payment may also have been regarded as some form of compensation for Ragnar's loss, and the invasion itself as an attack of revenge. In any case, this would be the first of a total of thirteen payments of so-called Danegeld to Viking raiders by the Franks (although the term itself is not expressly known to have been used at this particular point). While agreeing to withdraw from Paris, Ragnar pillaged several sites along the coast on the return voyage, including the Abbey of Saint Bertin.

Although Charles has been criticised severely for granting the large ransom payment to the Vikings, he did have 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. Since he would have trouble trusting his own counts to assemble and lead troops to defeat Ragnar's large force militarily, paying them off instead would buy Charles time, and possibly peace from further Viking raids—at least in the near future.

Aftermath
The same year, a Viking fleet also sacked Hamburg (by orders of King Horik I of Denmark), which had been elevated to an archbishopric by Pope Gregory IV in 831 on the initiative of Louis the Pious in order to oversee the Saxon territory and to support the introduction of Christianity to Scandinavia. In response, the East Frankish king Louis the German sent a diplomatic mission, headed by Count Cobbo (one of two court counts), to the court of Horik, demanding the Danish king to submit to Frankish overlordship and pay reparations for the invasion. Horik eventually agreed to the terms and requested a peace treaty with Louis, while also promising to turn back the treasure and captives from the raid. Horik most likely wanted to secure the border with Saxony as he faced a conflict with King Olof of Sweden and domestic struggles. By the treaty, Louis demanded Horik's obedience, which was further secured by Horik regularly sending embassies and gifts to Louis, and his suspension of support to Viking raiders.

Although many Vikings had died in the plague during the siege of Paris, Ragnar lived to return home to King Horik. According to a story originating from a member of Cobbo's embassy, Ragnar, having attacked the Abbey of Saint-Germain-des-Prés, then in the outskirts of medieval Paris, and which Cobbo later visited, attributed the plague to the power of Saint Germain of Paris. 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, he reportedly collapsed crying while relating that the only resistance he had met was by the long deceased saint. As Ragnar and several of his men died not long after, the king was so frightened that he ordered the execution of all the survivors, and the release of all his Christian captives. This event, in part, led Horik to receive Archbishop Ansgar, "Apostle of the North", on friendly terms in his own kingdom.