Charles's brother Louis the German of East Francia invaded his lands and many vassals fell from him. Thus the siege was broken off in September. After Björn's meeting with Charles in Verberie his name is not found in contemporary sources. However, the Viking warriors in the Seine continued their raids during the following years and even plundered Paris again in 861. In his despair Charles the Bald tried to use another Viking chief, Veland, whose men operated in the Somme region, to attack the Seine Vikings at Oissel. However, this scheme backfired since the two Viking armies made a deal and united their forces. The Norsemen were encamped by the lower Seine in 861–862, but then split again. Veland agreed to become a Christian and joined royal service, while the Seine Vikings went to sea. Some of them joined the fighting between the ruler of Bretagne and some Frankish counts. Expedition to the Mediterranean A number of Frankish, Norman, Arab, Scandinavian and Irish sources mention a large Viking raid into the Mediterranean in 859–861, co-led by Hastein, Björn Ironside and possibly one or more of his brothers. After raiding down the Iberian coast and fighting their way through Gibraltar, the Norsemen pillaged the south of France, where the fleet stayed over winter, before landing in Italy where they captured the city of Pisa. Flush with this victory and others around the Mediterranean (including in Sicily and North Africa) during the Mediterranean expedition, the Vikings are recorded to have lost 40 ships to a storm. They returned to the Straits of Gibraltar and, at the coast of Medina-Sidonia, lost 2 ships to fire catapults in a surprise raid by Andalusian forces, leaving only 20 ships intact. The remnants of the fleet came back to French waters in 862. Björn Ironside was the leader of the expedition according to the later chronicle of William of Jumièges. The early 11th century Fragmentary Annals of Ireland say that two sons of Ragnall mac Albdan, a chief who had been expelled from Lochlann by his brothers and stayed in the Orkney Islands, headed the enterprise. William of Jumièges refers to Björn as Bier Costae ferreae (Ironside) who was Lotbroci regis filio (son of King Lodbrok). William's account of the Mediterranean expedition centers around Björn's foster-father Hastein. The two Vikings conducted many (mostly successful) raids in France. Later on Hastein got the idea to make Björn