The Vikings are some of the most infamous warriors in history. Between the 9th and 11th centuries A.D., they launched a series of raids across the length and breadth of Europe, establishing a fearsome reputation that survives to the present day.
So, who were the enemies they took on?
The Vikings’ enemies included Anglo-Saxons, Franks, Frisians, Bohemians, Bavarians, and the Slavic tribes of Eastern Europe.
They took on almost all the European powers of the time, including Umayyad Spain, and Byzantium. Further from home, they fought Arabs, Italians, Mongols, and Native Americans.
This article will list the Vikings’ major adversaries and explain some of their successes in battles that helped establish their legend.
Also, see Why Was Valhalla Important to the Vikings? to learn more.
Who Did the Vikings Battle Against?
In their heyday, the Vikings reached almost every corner of Europe and fought virtually everyone they met.  
However, they weren’t the senseless barbarians their monotheistic adversaries painted them out to be. Instead, their piracy was motivated by practical considerations.
The limited resources available for social advancement in their Scandinavian homelands had set them on the path to raiding.
They also had limited numbers of men at their disposal and no large armies.
So, quick and brutal raids were the only way to minimize the loss of lives in battle.
Their favored tactic was to approach by boat, catching opponents unaware. Boats made it easy to make a quick getaway and avoid messy engagements with larger armies.
Even the Vikings’ terrible violence was instrumental – it aimed to terrorize future opponents into surrendering without putting up a fight.
In fact, Vikings were more than willing to make alliances when it served them better than going to war.
In picking targets, the Vikings’ geographical reach was limited by the available seafaring technologies of the time.
Even though they were the most advanced sailors of their day, it was challenging to transport men and supplies across great distances unless local bases or alliances had been established en route.
Finally, Vikings preferred targeting rich, poorly defended territories to maximize profits.
This combination of factors made monasteries, cathedrals, and towns, especially along the easily accessible coasts of present-day Ireland, Britain, and France, ideal targets.
Viking Raids in Rhineland
Of course, the Vikings did not neglect opportunities closer to home.
Traveling up the Rhine, they targeted villages and towns in what are now the Netherlands, Belgium, and Germany on multiple occasions, beginning in the mid-9th century.
Across Frisia, Bohemia, and Bavaria, they fought armies, destroyed crops, and captured and enslaved local populations. 
However, Britain and France were bigger prizes, so the Vikings targeted them more frequently.
The Vikings in the British Isles
The Vikings first appear in the pages of history with a raid on a monastery in Lindisfarne on the northern English coast in 793 CE. Beginning in 830 CE, they regularly attacked London, arriving in large fleets, looting, pillaging, and leaving much slaughter in their wake. 
In 865, they invaded East Anglia and conquered Mercia and Northumbria too. Eventually, they were defeated by Alfred the Great in the Battle of Ethandun.
Despite their loss in battle, the Vikings signed a treaty with the Anglo-Saxons that gave them control of large parts of northeastern England until the mid-11th century.
The territories under Viking rule came to be known as the Danelaw – the place where the law of the Danes applied.
The Vikings in France
Following the death of Charlemagne, Holy Roman Emperor and King of the Franks, in 814 CE, the Vikings launched two decades of successful raids across Frankish territories.
In 845 CE, they got as far as Paris.  By then, Charlemagne’s sprawling territories had been divided, and the Frankish armies were no longer as strong as they used to be.
Beleaguered Frankish kings often bought peace with land, gold, and silver.
Unfortunately for them, the Vikings read this as an opportunity to make more frequent demands for ransom.
Despite building bridges across the Seine, the Franks could not deter later raiding parties. And in 885 CE, a Viking fleet held the city in a yearlong siege, only leaving when Charles the Fat acceded to their demands.
Eventually, Charles, the Simple signed the Treaty of Saint Clair sur Epte with the Vikings.
Their leader, Rollo, became a Christian, married Charles’s daughter, and established the Norman dynasty in Francia.
Vikings in the East
While the Danes and Norwegians expanded westward, Swedish Vikings, known as Varangians, traveled down the Volga and Dnieper Rivers into the Baltics, where they established the Kievan Rus state. 
Their territories spanned areas of present-day Russia, Belarus, and Ukraine.
In the process, they defeated many of the Slavic tribes of the region. They enslaved so many people in the region that the word Slav would later morph into the word slave.
The Varangians reached as far south as Constantinople, where they allied with the Byzantine rulers and joined their ranks in battle.
The Vikings were so well regarded in Constantinople that they were entrusted with providing men for the king’s personal bodyguard. 
Despite this, the Vikings did have disagreements with Constantinople and fought them on occasion. They also had fraught relations with their Turkish neighbors.
Varangian rule over these Eastern European territories lasted well into the 13th century and was only terminated by the Mongol invasions.
The Furthest Viking Expeditions
Spurred on by their successes in Northern Europe, two Viking chiefs, Bjorn Ironside and Hastein, sailed down the Mediterranean and attacked Umayyad Spain in the 850s CE. 
The Andalusian historian Abu Abdullah al-Bakri describes a Viking attack on Nekor, now in Morocco, in the 860s CE. 
Both attacks had limited success, and the Vikings never established permanent bases along the Iberian Peninsula or the North African coast.
Later accounts suggest that Ironside and Hastein went on to attack the Italian city of Luni, mistaking it for Rome. In any case, the Vikings did not establish a permanent presence in Italy.
The Vikings also expanded further westward than any Europeans had before them.
After Ireland and Scotland, they established footholds in the Faroe Islands, Iceland, and Greenland.
They even made it as far as North America, where they did not enjoy good relations with native tribes.
The Vikings eventually retreated from both North America and Greenland.
They went on to permanently settle in Iceland, which had been uninhabited when they arrived.