Ushered in with raids on Christian monasteries, the Viking Age came to an unlikely end centuries later with the Nordic warriors joining in the Crusades and fighting in the name of Christianity.

The Viking Age brought change not only to the regions of Europe plundered and conquered by the Nordic warriors, but to Scandinavia itself. “From the Scandinavian point of view, the big story of the Viking Age is its assimilation into the European mainstream,” says John Haywood, who chronicles the exploits of the Scandinavian raiders on four continents in his new book, “Northmen: The Viking Saga AD 793-1241.”

“You have Vikings going out all over the world, and in a sense the world is coming to Scandinavia. Those ideas they encounter go home, and the biggest of course is Christianity, which changes Scandinavia very dramatically.” Along with the new faith came Roman and canon laws, Latin alphabets and literature and Christian art. “It changes the culture of Scandinavia in just a few decades,” Haywood tells HISTORY.

Scandinavian kings, in particular, saw great appeal in abandoning their pagan gods. “Christianity does a lot to bolster the position of kings in Scandinavia,” Haywood says. “The idea that authority comes from God is quite welcome to kings. It gives them an extra claim.” Unlike Christianity, Viking religions lacked a priesthood. Local chiefs served as intercessors. With the adoption of a new religion with a priesthood, chiefs lost a great deal of power to kings.

Most of Scandinavia had been converted to Christianity by 1095 when Pope Urban II issued a plea for Christian armies from an ascendant Western Europe to aid Byzantine Emperor Alexius I in fending off the Seljuk Turks and recapture the Holy Land from Muslim rule. The pope decreed that those who joined in the expedition would receive remission of all penances due for their sins. Full of religious fervor, the converted Vikings were among the upwards of 100,000 Christians who answered the papal call and joined in the First Crusade.

After the holy warriors captured Jerusalem in 1099, they were encouraged to take on other perceived enemies of the Christian faith in Europe, such as the Moors in Spain and Slavs and Balts in Eastern Europe. “Scandinavian kings were among the first to see that crusading was good politics as well as good religion,” Haywood writes. Only three years after the capture of Jerusalem, Denmark’s King Erik the Evergood became the first king of any Catholic country to set off on a pilgrimage to the Holy Land, doing so as penance for killing four retainers in a drunken rage. He never made it, however, after falling ill and dying en route in Cyprus.

Taking of Jerusalem by the Crusaders, 15th July 1099. (Credit: Public Domain)

Norway’s King Sigurd I, who shared the throne with two other illegitimate sons of their late father, became the first European king to lead a Crusade when he sailed off from his homeland in the autumn of 1107 with 3,000 men. Although eager to prove his fealty, the teenaged monarch did not appear to be in a rush to reach the Holy Land. Sigurd spent the winter of 1107 with England’s King Henry I and made it as far as the Kingdom of Galicia in the northwest of present-day Spain by the following winter.

“From here on,” Haywood writes, “the crusade turned into a Christianized Viking expedition, no doubt made all the more enjoyable by the conviction that God surely approved of every injury they inflicted on the infidels.” As the Norwegian Crusaders sailed south along the coast of the Iberian Peninsula, they captured Moorish pirate galleys and castles. They attacked Lisbon and sacked a Moorish castle at Colares, massacring the troops that refused to convert to Christianity. “Sigurd is a Christian king, but he still fights like a Viking,” Haywood says. “His motives are different. The way he justifies it are different, but in many ways you can still see the Viking past there once in a while.”

After sailing to Sicily and through the Greek archipelago, “Sigurd the Crusader” arrived in the Holy Land at the port of Acre in the summer of 1110 with the loss of only one of his 60 ships. The Norwegian king and his retainers received a warm welcome as they entered Jerusalem. Sigurd was given holy relics, including a splinter from the True Cross on which Jesus was said to have been crucified, and rode with Jerusalem’s King Baldwin I to the River Jordan where he may have been baptized. Before departing, the Norwegian king joined Baldwin in the siege of Sidon and used his fleet to successfully blockade the coastal city and expand Christian gains in the Holy Land.

Stopping in Constantinople on his trip home, Sigurd gifted his ships to the Byzantine emperor, and many of his men signed on with the emperor’s Varangian Guard. After traveling overland through Europe, the Norwegian ruler sailed home in a ship given to him by Denmark’s King Niels. “Sigurd consolidates his kingship and returns a great hero,” Haywood says. “It bolsters the prestige of the king in his kingdom.”

The Scandinavians continued to launch Viking-style raids in subsequent years against pagan lands in Europe. After the launch of the Second Crusade, the pope offered the same spiritual incentives against pagan Wends in the southern Baltic region, and Danes joined in the Wendish Crusade in the middle of the 12th century. Danish King Valdemar II subsequently joined in the Crusades called for by Pope Celestine III against the Livonians living in present-day Latvia and Estonia at the turn of the 13th century.

“There was much to be gained by kings to be seen as champions of Christendom,” Haywood says. “For Danes and Swedes in the Baltic region, they took lands from the Slavs, Finns and Estonians and increased the size of their kingdom as well. So there’s a territorial motive as well as a religious one.”