A Danish Empire understood as a political unity with a number of peoples speaking various languages under Danish rule has existed since the beginning of the first millennium. This entry covers the period from the end of the Viking period (c.1100) until today.

The kingdoms of Denmark and Norway were united from 1380 to 1814. The history of the “Danish” Empire only makes sense if it is remembered that for more than 400 years it was not a “Danish” but a “Danish-Norwegian” Empire, and that the heartland of the empire was not only present-day Denmark, a small peninsula and some islands between the North Sea and the Baltic Sea, but also present-day Norway with a coastline of more than 2000 km facing the North Atlantic and the Arctic Sea.

The history of the Danish(-Norwegian) Empire since c.1100 can be divided into two parts. It was growing until the first quarter of the 16th century; but centuries of decline followed, sometimes slow, sometimes catastrophic, until the 20th century when the empire was reduced to the contemporary micro-empire consisting of the kingdom of Denmark and two small North Atlantic societies with home rule: the Faroe Islands north of Scotland; and Greenland – the immense, wedge-shaped, ice-covered island in the north-eastern corner of the western hemisphere (2.2 million sq. km) facing Canada across the Davis Strait.

The Danish(-Norwegian) Empire was a seaborne empire, a thalassocracy. Canute the Great and the other Viking chiefs and kings had built their empire on seaborne attacks using their pre-eminent shipbuilding technology and maritime skill. So did the medieval Danish empire builders. A navy in the modern sense of the word was founded in the 15th century and it remained one of Europe’s biggest and best equipped until the Napoleonic Wars when it was destroyed by the British (1807). Naval power and the quest for naval supremacy was for centuries the cornerstone of all Danish(-Norwegian) political and military thinking.

After the end of the Viking period and the eclipse of Danish influence in the British Isles, from c.1100 to 1380, Denmark turned all her ambitions eastwards under a political doctrine later to be known as Dominium Maris Baltici (dominance of the Baltic Sea, the inland sea of the Nordic region). From the second half of the 12th century the empire expanded east along the North German coast through a series of naval attacks on progressively more distant locations. Its culmination was reached in the year of 1219 when Estonia was conquered by King Valdemar II (the Conqueror). At that point the Danish Empire included most of the southern coastline of the Baltic Sea from Holstein past Rügen (conquered 1169), through Pomerania and the Baltic States as far as Russia, just as all the islands of the Baltic Sea except Gotland (finally conquered 1361) were under Danish rule. The Baltic was for all practical purposes a Danish mare nostrum. This eastward expansion, which took place in competition with the German Teutonic knights, was organized and understood as a series of crusades. The participants were given religious dispensation “like those who go to Jerusalem,” and the soldiers were urged to fight for “our Jerusalem of the North.” Merciless fighting and cruel treatment of the defeated was followed by the founding of monasteries and intense missionary activity in the local Slavonic and Finno-Ugrian languages.

The Danish dominance of the Baltic Sea, organized as a feudal state and based on oaths of allegiance from local leaders to the Danish king and his representatives, was never uncontested, and in periods, especially in the 14th century, it was seriously challenged by the Hanseatic League. A significant reduction was the loss of Estonia (1346) which was never regained except for the strategically important island of Saaremaa (Øsel) and a small strip of land (1559). But that did not mean that the Danish Empire was eliminated in the Baltic. Gotland remained in Danish(-Norwegian) possession until 1645, confirming the still existing supremacy of the Danish Empire in the Baltic.

Until the second half of the 14th century the Danish Empire concentrated on the Baltic Sea and it did not pay much attention to the Scandinavian Peninsula except for the southern part of present-day Sweden (the territory of Skåne, Halland, and Blekinge) that since time immemorial had been a part of the Kingdom of Denmark. The union of Denmark and Norway began in 1380 as a consequence of an accidental dynastic connection: Olaf, the son of Haakon VI, the king of Norway, became the king of Denmark at the death of his maternal grandfather Valdemar IV five years before he, still only a boy at the death of his father in 1380, became king of Norway. The union proved stable and endured for more than four centuries during which the Baltic focus was supplemented with a North Atlantic perspective. Alongside the old doctrine of Dominium Maris Baltici a parallel doctrine called Dominium Maris Septentrionalis – dominance of the northern waters – was conceived, reflecting the fact that Norway had a long Atlantic and Arctic Sea coastline and brought with her a seaborne North Atlantic empire. This so-called Norgesveldet consisted of the Orkney Islands, the Shetland Islands, the Faroe Islands, Iceland, and, “the jewel in the Norwegian crown,” Greenland, home of the white bear and the place from where Europe got narwhal-tooth, the ebony of the north, and white hunting falcons, much loved by medieval kings and emperors.

Taken together these two doctrines circumscribed the idea of a geographically vastly extended seaborne northern empire – a Roman Empire of the North – with a number of different peoples and languages. The outer limits were, to the east, the Gulf of Finland and Russia, to the south, Holstein and the city of Hamburg, to the west the islands north of Scotland, Iceland, and Greenland, and, to the north, the Arctic Sea and the Svalbard archipelago. Only sporadically did the Danish-Norwegian Empire venture outside this Baltic-Scandinavian-North Atlantic area. Within these limits, however, the empire had the highest possible ambitions that were soon to be more than fulfilled.

Periodically, the royal houses of Sweden and Norway had been united, and it so happened that at the time of the dynastic unification between Denmark and Norway (1380) the possibility of a new Swedish-Norwegian dynastic union was emerging. An influential group of Swedish aristocrats looked to Norway, now empowered by the union with Denmark, for an alternative to the ruling king of Sweden, Albrecht of Mecklenburg. Denmark traditionally did not pay much attention to her Scandinavian neighbors, but with the dynastic union between Denmark and Norway under a Norwegian-born king the perspective changed. Sweden was a place of primary interest, and in 1385 Olaf, the young Danish-Norwegian king, adopted as a title: “true heir to the throne of Sweden.” Unfortunately he died in 1387, only 17 years old, and never became ruler of all three realms. That honor was bestowed on his mother, the politically astute and highly competent Queen Margrete, who from 1395, still not forty years old, stood as “true mistress” of Denmark, Norway, and Sweden. In 1397 the union of the three Nordic kingdoms was confirmed as the “Union of Kalmar” and a nephew of Margrete, Erik VII (of Pomerania), was crowned king of Denmark, Norway, and Sweden. This extended kingdom consisted of much more than the names suggested: Denmark included the Baltic Sea, Sweden included Finland, and Norway included the North Atlantic and its islands. And this was not only airy theory as among the persons signing the Kalmar coronation document was a representative from the Orkney Islands.

In spite of internal problems, especially with the nobility that energetically resisted the macro-tendency of the time toward stronger, more centralized states, and in spite of what historians – always eager to describe the Kalmar Union as a fiasco – claim, it was a surprisingly stable and well-functioning political construction that existed for more than a century. It continued until a foolhardy, passionately anti-aristocratic king, Christian II, three days after his glorious, imperial-style coronation in his Swedish capital, Stockholm, in November 1520, put a bloody and unexpected end to it by executing more than eighty members of the Swedish aristocracy in the biggest public square of the city.

The Kalmar Union may be understood as a temporary extension of the longer lived Danish-Norwegian Empire or it may be seen as a Baltic-Scandinavian-North Atlantic empire in its own right. In any case it remains a fact that the Kalmar Union was one of the biggest and most powerful political entities of the day in Europe and that the influence and prestige of the northern world in the 15th and early 16th centuries reached an unprecedented and unrepeated climax. The kings of the Kalmar Union (one of them, Christoffer III, took the otherwise unknown title archirex, arch-king) were treated as equals of emperors and popes, and they entered into marriages never seen before in these parts of Europe. Most spectacularly, Christian II married Elizabeth of Habsburg, a sister of German-Holy Roman Emperor Charles V, just as he was honored on his coronation day in 1520 – three days before he destroyed the Kalmar Union with the “bloodbath in Stockholm” – with the award of the exclusive Order of the Golden Fleece by his brother-in-law.

For the Danish-Norwegian Empire the following two centuries – from the collapse of the Kalmar Union in 1520 to the end of the Great Northern War in 1720 – was one long, ever more hopeless and exhausting fight to maintain the Dominium Maris Baltici, now with an angry and aggressive Sweden as the main adversary, the old competitors, the Hanseatic League and the Teutonic Knights, having left the stage. Indeed, the rise of Sweden in the 16th and 17th centuries as an increasingly indispensable supplier of copper, iron, tar, furs, and timber for the West European market turned her into a much more formidable and frightening enemy than the Hanseatic League and the Teutonic Knights had ever been. In the first decades after 1520 it was the goal of the Danish-Norwegian Empire to maintain its dominion in the Baltic by trying to force Sweden back under Danish-Norwegian control by re-establishing the Kalmar Union by force. This was the goal of the Seven Years War of the North (1563–1570), and again of the so-called Kalmar War (1611–1613). Denmark-Norway was victorious in both wars but not sufficiently superior to force Sweden back into the Kalmar Union, and from the end of the Kalmar War the question of Sweden’s existence as an independent state no longer featured on the Danish-Norwegian government’s agenda.

That was only the beginning. In the following decades the phenomenal transformation of Sweden into an important European power turned everything upside down: the question was no longer the eradication of Sweden as an independent nation state, but how to avoid Sweden incorporating Denmark-Norway and creating a Swedish-led Baltic-Scandinavian-North Atlantic empire with Stockholm as its capital. In 1645, after further hostilities, Denmark-Norway was stripped of all its islands in the Baltic except for Bornholm, and in 1658 Sweden obtained the old Danish territories on the eastern side of the Sound. The new border between Sweden and Denmark(-Norway) was established in the middle of the Sound, the narrow entrance to the Baltic.

Denmark-Norway was humiliated and had lost Dominium Maris Baltici, but not to Sweden – the real winners of the endless wars between Denmark-Norway and Sweden were the Dutch Republic, England, and France. While the two Scandinavian powers had tried to eliminate each other, the control of the Baltic Sea was assumed by the leading trading nations of Western Europe, for whom the Baltic, with its reserves of timber, tar, hemp, flax, grain, furs, and iron, played a similar role in the 17th century as the Persian Gulf plays for the industrial nations of the Western world today. Dominium Maris Baltici was taken out of the hands of the former masters of the Baltic Sea and, to use a modern expression, internationalized. The border between the two local powers was set in the middle of the Sound – the Hormuz Strait of the day – not because Sweden had lost its appetite for conflict with Denmark-Norway but because England, France, and the Dutch Republic considered it desirable to ensure permanent access to the Baltic Sea for themselves. In the following decades Denmark-Norway tried to get back at least some of the lost territory, first in the Scanian War (1675–1679) and later in the Great Northern War (1701–1720). In spite of successes on the battlefield all gains were lost at the negotiating table. The great powers would not allow either Denmark-Norway or Sweden – now both downgraded to middle-rank powers in the European concert – to change anything in the Baltic Sea without their sanction. In 1720 this was finally accepted by Denmark-Norway.

Dominium Maris Septentrionalis, the North Atlantic dimension of the Danish-Norwegian Empire had never been forgotten. Christian II – the last of the Kalmar Union kings – had fully developed plans to resume connections with Greenland, which had been abandoned by its Norse population during the 15th century, and Dutch and British whaling in the North Atlantic was followed closely by Danish-Norwegian authorities from the beginning of the 17th century. On the other hand it is clear that the North Atlantic dimension did not always have top priority, the financially expedient (not strictly necessary and – as it turned out – irreversible) pawning of the Orkney and the Shetland Islands to the king of Scotland in 1468–1469 being an example. All this was totally changed after the stalemate in the Baltic Sea in 1720, and the 18th century – the last century of the Danish-Norwegian Empire – became the great period of the North Atlantic part of the empire. In 1721 a missionary Hans Egede was sent to Greenland with three ships. This became the beginning of a huge effort to build up Greenland as the western frontier of the empire. Protected by the Danish-Norwegian navy and with a practically unlimited access to money from the state treasury in Copenhagen, a wall of 14 fortified towns facing the Davis Strait was raised between 1728 and 1797.

Seen in an Atlantic perspective, the Greenlandic wall of towns completed the chain of colonial settlements along the eastern coast of the Americas that had been in the making since the arrival of Columbus in 1492, the first towns being Santo Domingo (1502) and Vera Cruz (1519). The last stretch to be covered on the long distance from Cape Horn in the south to the Polar Sea in the north by European colonial settlements was the section north of the Gulf of Saint Lawrence. No towns were established there before the foundation of the first Danish-Norwegian town in Greenland, Godthaab (Nuuk). With the foundation of Nanortalik close to Cape Farewell in 1797 the encirclement of the Atlantic with European towns founded by the Spanish, Portuguese, French, English, Dutch, and, eventually, Danish-Norwegian empires was completed. Seen in a closer Danish-Norwegian perspective the tour de force in Greenland – together with similar efforts in Iceland – bears witness to the importance assigned to the North Atlantic part of the Danish-Norwegian Empire in the 18th century. The main attention was moved from the static Baltic Sea to the movable and dynamic North Atlantic.

The Danish-Norwegian Empire transcended its core area, the Baltic Sea and the North Atlantic, on a limited scale. In 1618 an expedition was sent to India by King Christian IV. This expedition was the beginning of a Danish-Norwegian settlement in Tranquebar on the Indian south-east coast, followed by a few other establishments in the same region including the Nicobar Islands in the eastern Indian Ocean (from 1754/1756). In Africa, on the Gold Coast (today’s Ghana) there was a Danish-Norwegian trading settlement from 1658. In a place called Osu not far from present Accra a fortress, Christiansborg, was built. Christiansborg and a number of sub-establishments further east were used as transit places for gold, ebony, and slaves. In the Caribbean, Denmark-Norway acquired three islands: Saint Thomas (from c.1670), Saint Croix, bought from France (1733), and Saint John (from 1717–1718).

The number of slaves shipped from the Danish-Norwegian positions in Africa has been estimated at 85,000 for the years 1660 to 1802, when the Danish-Norwegian trade was stopped, and the amount of sugar produced, especially on the fertile Saint Croix, was quite considerable. However, the main importance of the tropical extensions of the Danish-Norwegian Empire was, as shown by the Danish historian Ole Feldbæk, their function as a hub for illegal English, French, and Dutch trade during the wars of the last half of the 18th century where Denmark-Norway succeeded in remaining neutral.

This worked splendidly and created much transit trade and a considerable amount of “easy money” to Danish-Norwegian, especially Copenhagen-based, trading companies as long as Denmark-Norway managed to stay outside the repeated European-Atlantic hostilities; and it was nearly forgotten how fragile the Danish-Norwegian Empire was, and that – in spite of its still very respectable navy, even on a European scale – it was unable to defend itself. The British attack on Copenhagen in 1801 and again in 1807, where the Danish-Norwegian navy was annihilated and partly taken away to England, served as a wake-up call. The British Royal Navy controlled the seas, and from 1807 Denmark-Norway no longer had access to her seaborne empire; the destiny of the Faroe Islands, Iceland, and Greenland as well as the tropical colonies was in British hands. Even the inner Danish waters were filled with British ships, and the absolutely vital connection across the Skagerrak between Denmark and Norway was partly interrupted. This inability to defend herself during the Napoleonic War was the end of Denmark-Norway as a political unity, just as it reduced the empire to a shadow of its former self.

The Napoleonic War was ended in the north with the Peace of Kiel on January 14, 1814, dictated by Great Britain and Russia. The Danish-Norwegian union was dissolved, and Norway was ceded to Sweden as compensation for Sweden’s loss of Finland to Russia in 1809. It was widely expected that Britain would keep the Danish-Norwegian North Atlantic empire that had been governed from London since 1807, and that it would be included in the British Empire. That did not happen. Instead Greenland, Iceland, and the Faroe Islands were given to Denmark in spite of the fact that this part of the former Danish-Norwegian Empire was more Norwegian than Danish, and in spite of the fact that Denmark had no desire whatsoever to become an Arctic nation. The former Danish-Norwegian tropical colonies were also given to Denmark.

For post-1814 Denmark – Europe’s smallest independent state, very different not only in size but also in outlook from the former surprisingly self-assured Denmark-Norway – the empire was an embarrassment, especially its tropical parts: impossible to defend and economically valueless. The possessions in India and in Africa were handed over to Great Britain as soon as was possible: India in 1845 and Africa in 1850. The Caribbean Islands could not be handed over to Great Britain because of the Monroe Doctrine; the only way to get rid of them was to sell them to the United States. That happened after protracted negotiations in 1917. The sum paid by the United States for the three islands, now the Virgin Islands, was US$25 million.

As old Nordic territory, Greenland, Iceland, and the Faroe Islands represented a special problem with sentimental overtones. The final outcome was that Denmark after some decades of hesitation decided to reinvent herself as an Arctic nation and to embrace her completely indefensible North Atlantic empire. When, in 1944, during World War II, Iceland left the Danish Community it was deeply regretted. Today, Greenland and the Faroe Islands (protected by NATO and the United States) are, as members of the Danish Community (Rigsfællesskabet), an important element of Danish national identity.