Few neighboring countries were at war so often with each other from the Middle Ages until the end of the Protestant reformation as Sweden and Denmark--in much the same way as France and Germany from Napoleonic times until World War II. For most Americans this comes as a surprise, since both countries along with the rest of Scandinavia enjoy a modern image of peaceful states that enjoyed neutrality throughout most major modern European conflicts. The many similarities in culture, language, religion, the common reputation as "welfare states" with advanced social legislation and a social security net to prevent outright deprivation have obscured much of the same differences in outlook that distinguish Americans and Brits in spite of a long common history and shared institutions.
Like the differences that led to the American Revolution and the final separation from England in spite of the presence of a large contingent of loyalists who remained loyal to their king and oath of allegiance, Danes and Swedes could not agree on the form of the union between them. The differences separating them did not constitute an ocean but a common land boundary and narrow stretches of water. What we call Southern Sweden today is known by the regional name of Skåne (with its own flag). It was both in terms of physical geography, landscape, soils, vegetation and climate a part of the Danish Kingdom from the earliest appearance of a state embracing Jutland (Jylland), Skåne across the Øresund and the main Danish islands Funen, (Fyn) and Zealand (Sjæland), lying amidst the two "Belts" in the Kattegat.
Like the case of the English governors and the American colonial houses of representation, the Swedish and Danish nobility were diverse sources of power. Growing resentment of the Union led to the desire for renewed Swedish independence and the eviction of Danish control of Skåne, a move that would award Sweden a share in the control of the narrow straits, through which European maritime traffic passed from the North Sea and the Baltic.
It also meant the end of Danish monopoly. With two such contrasting visions of their future and status, the union collapsed and war followed war from 1434 until 1720. Even with Denmark's ability to mobilize allies, most notably the Russians, the results were almost continuously successful for Sweden, and a terrific blow to Denmark's prestige and image as the leading Scandinavian power.
The result was also a strong national enmity that built upon existing resentments. A final blow was dealt when Sweden picked the winner in the Napoleonic wars and Denmark was forced to cede control of Norway to its bitter enemy, adding a final humiliation and promoting Sweden to the undisputed position as the "big brother." This diplomatic victory was bitterly resented in both Denmark and Norway as an example of Swedish imperialism.
Although Denmark proper (Jutland, Fyn and Zealand) was never conquered by Sweden, it too suffered humiliation by its archrival as a result of constant military defeats that eclipsed its early domination of the Baltic. This ignominy served as a cause of irredentist hopes for centuries and prolonged the hatred between the two countries.
To this day, the Danish royal anthem sings of a naval victory of their King Christian IV over the Swedish fleet in 1644. By contrast, the Swedish anthem never even mentions the name of the country but exclaims, "I will live and die in 'Norden'" (a term, like Scandinavia, referring to the entire region).
World War II added a modern chapter when Denmark and Norway fell to a German invasion, while Sweden maintained a profitable neutrality and allowed transport of both German troops and German-controlled Norwegian and Finnish raw materials across its territory issues, which created an additional layer of resentment, rivalry and competitiveness.
The Danes have always had a reputation among their Scandinavian colleague as being much more European, especially because of French influence, and therefore are regarded as somewhat decadent, less puritanical, lackadaisical, sloppy, and more interested in good food and pursuing beautiful women than the aloof, industrious, neat, well-groomed, rational (the Danes would add "arrogant") Swedes--or the athletic, honest, nature-loving and athletic Norwegians. Of course, like all stereotypes, there is both exaggeration and enough of a grain of truth in these images to convince observers to look for confirmation.
The popular press, especially the mass circulation tabloids, delights in playful teasing and taunting the older brother rival that sometimes reaches grotesque proportions. Although educated people regard this pandering to old prejudices as the cheapest form of sensationalism, its continued emotional long-term appeal cannot be doubted.
A favorite part of this teasing is the double-meanings employed in manipulating the two closely related languages. Danes and Swedes will often prefer to converse in English rather than speak their own languages with each other. The written form is sufficiently similar so that the general meaning of texts can be generally understand but differences in intonation, pronunciation and the distinct different meanings of closely sounding words provide an endless form of humor. Swedes have a special "Sj" sound and most Danes use a pronounced glottal stop that are difficult for non-natives to imitate.
In 1944, a Dane and a Swede, Ellen Hartmann and Valfrid Palmgren Munch-Petersen, wrote a special dictionary titled Farlige ord og lumske ligheder i dansk og svensk (Dangerous words and awkward similarities in Danish and Swedish) that should be read by anyone needing to master the neighboring language and avoid embarrassing mistakes. One can imagine the reaction of an American woman to an expression like: "I came by yesterday to knock you up but nobody was home." For an Englishman until circa 1970 this simply meant: "I came by and knocked on the door to see if you were home."
All this may seem like making a mountain out of a molehill for many foreign observers who imagine that the Scandinavian peoples are so similar they should have long ago buried the hatchet. Indeed, all the Scandinavian states remain among the most stable in the world politically. They cooperate in many economic and social areas such as the joint SAS airline and are culturally, socially and linguistically similar, but maintain a distinct sense of political separateness.
History and especially geography has determined much of their foreign policy and prevented them from following a common one or joining in an alliance. Norway and Denmark joined NATO due to their inability to maintain their neutrality in World War II, while Sweden continues to be neutral. All three jealously guard their independence. Denmark's close proximity and border conflict over Schleswig (Slesvig) prevented Norway and Sweden from considering a Scandinavian alliance before the World Wars with their prospect of German expansionism and revenge.