The Seine River was one of the routes that the Vikings were most interested in plundering, having raided Paris on previous occasions.
In 845, it was attacked for the first time by the men from the north commanded by Ragnar Lodbrok (obtaining a tribute of 7000 pounds in silver for abandoning the city) and later in 857, 861 and 865. In 882, the death of Louis III of France and the disunity of the kingdom was taken advantage of by the Vikings to sack Rouen and organise the capture of Paris.
By 885 the Vikings advanced up the Seine and reached Paris on 24 November with 700 ships, led by Siegfried. The situation in Paris prevented the Vikings from advancing further along the river without taking the city. The city had recently modernised fortifications, both on the islands (which were the heart of the city) and on the bridges, but they were not yet complete. The defence had previously fallen to Hugo the Abbot, but this time he was seriously ill (he died the following year) and handed over the command to Bishop Gozlin of St-Denis, who shared it with Eudes, Count of Paris, son of Robert the Strong; however, Gozlin died in 886 during the siege, and all responsibility fell to Eudes.
It was not until 885 that they resumed their attacks on the cities along the Seine. On 24 November they reached Paris with a fleet of some 600 ships with Siegfried and Rollo in command, the tactics of the fortifications meant that if they wanted to continue along the river inland they first had to take Paris. The vast majority of the population lived on the Île de la Cité, an island connected by two bridges to the riverbanks. The first attack focused on the defence tower, which was repulsed with great effort, and despite the damage it was rebuilt by night. The next day they tried to break through the foundations but were again repulsed by the defenders, who threw stones and a mixture of oil, wax and fish at them.
The first Viking assault was against the tower defending the bridge leading to the Île de la Cité, which if successful would allow the Vikings to continue their crossing. The tower was not finished but withstood the onslaught and after a hard fight, the Parisians repaired it and even added a floor. In subsequent attacks, the Vikings tried to break through the wall by ballistae and overrun it by assault, but the defenders used flammable materials and catapults to repel them. Abbo (the chronicler of the events) says that the tower was defended by about 200 men and that the Vikings numbered about 40,000, probably an exaggerated number, but surely there was a great disproportion between the forces.
For three days the Vikings kept up a constant assault on the defences, attempting to set fire to them and engulfing the battlefield in smoke, which the defenders took advantage of to make a sortie that forced the Vikings to temporarily desist. After the failures, the Vikings decided to move the camp to the shore and build new and powerful siege weapons, such as catapults and towers.
In subsequent attacks, the Vikings tried to approach with towers and using formations similar to the testudo used in the past by the Roman legions. The defenders’ sorties allowed them to take two of the siege towers, but the critical moment came when a breach was made in the defences and Count Eudes himself came and fought hand-to-hand to close it. When the plague began to ravage the city (resulting in the death of Bishop Gozlin) and the relief force sent in was annihilated by the Vikings, Charles the Fat, who was then the Carolingian emperor, decided to act, signing an agreement with the attackers whereby he would pay them a danegeld (tribute) and allow them to pass into Burgundy (which refused to recognise Charles’ authority).
Count Eudes and the Parisians, despite the signing of the treaty, refused to let the Vikings continue up the Seine, forcing them to take their boats overland as far upriver as possible.
Although the chronicler Abbo claims that the Viking force was enormous, one of the counter-evidence is that the Vikings were not able to completely surround the city during the siege. Although there is no agreement among historians, it is estimated that the force with which they initiated the siege was about 30,000 men.
The political consequences were significant, Eudes gained a reputation that probably led to his election as king of the West Franks, while Charles the Fat was considered cowardly and incapable, a fact that combined with his inability to produce an heir and his continuing illnesses led to his deposition in 887.
We know these facts mainly thanks to Abbo de Saint Germain des Prés, a Benedictine monk who was a direct witness to the siege of 885-886 and who later wrote the poem “De bellis Parisiacae urbis” recounting the siege.
Militarily speaking, this siege was one of the examples in the High Middle Ages of the importance of fortifications, which would continue to be of great value until the appearance of artillery centuries later, which forced the planning and construction of defences to be revised.