Denmark developed a reputation for violence as the Vikings ravaged regions of central and southern Europe.So ironically, the country with one of the least controversial images in Europe today was originally a hell-raising land that, along with such other Viking areas as Norway and Sweden, was associated with terror for the rest of Europe. Lustfully pagan and undeterred by the belief that Christian churches and monasteries were sanctified, they exacted rich plunder from whatever monastery or convent they happened to judge as weak enough to be attractive.
Their longboats were especially feared: Measuring about 18m (60 ft.) from the dragon-shaped prow to stern, longboats were powered by 30 oars and a sail. They were still light enough, however, that their crews could drag them across land, thereby "hopping" from rivers to lakes, across sandbars, and across isthmuses that would otherwise have been unnavigable. It's no small wonder that the Danes would eventually become proficient as both mariners and traders.
Through rape and intermarriage, the Vikings mingled bloodlines with future English, French, Germans, and Russians. Despite the mayhem they unleashed on conquered lands, Vikings brought with them regimented rituals; for example, unlike most European peoples at the time, they bathed every Sunday, regardless of temperature or weather.
The most distinct threat to Danish territoriality came from Charlemagne, whose Frankish empire covered what is today France and Germany. If Charlemagne hadn't focused most of his territorial ambitions on richer, more fertile lands within central Europe and Spain, it's likely that what's known today as Denmark would have become a vassal state of the Franks. As it was, the Franks only took a slight imperial interest in Jutland. In fact, Godfred, the first recorded Danish king, died in 810 after spending most of his reign battling the Franks.
Godfred's successor, Hemming, signed a treaty with the Franks marking the Eider River, an east-west stream that flanks southern Jutland, as the southern boundary of his sovereignty. That boundary functioned more or less as the Danish border until 1864.
Two famous kings emerged from Denmark during the 10th century, Gorm the Old (883-940), and his son, Harald Bluetooth (940-85). Their reigns resulted in the unification of Denmark with power centralized at Jelling in Jutland. Harald, through the hard work of a core of Christian missionaries trained in Frankish territories to the south (especially in Hamburg), also introduced Christianity, which eventually became the country's predominant religion. As part of his attempt to obliterate Denmark's pagan past, he transformed his father's tomb, which honored a roster of pagan gods and spirits, into a site of Christian worship.
Harald eventually extended Danish influence as far as neighboring Norway. The links he established between Denmark and Norway weren't severed, at least politically, until the 1800s. Harald's son, Sweyn I, succeeded in conquering England in 1013, more than 50 years before the Norman invasion in 1066. The Normans, ironically, were also of Danish origin, through invasions several centuries before.
Under Sweyn's son, Canute II (994-1035), England, Denmark, and part of Sweden came under the rule of one crown. After Canute's death, however, the Danish kingdom was reduced to only Denmark. Canute's nephew, Sweyn II, ruled the Danish kingdom, and upon his death his five sons governed Denmark successfully. In 1104, the foundation was laid for a Danish national church that was distinct from the ecclesiastical administration in Hamburg.