Medieval fake news?

Dick Harrison is a Swedish history professor who has written a long series of popularized books about "the dramatic history" of both Sweden and the world, unfortunately only available in Swedish. "Visby Brandskattning", published this year, tells the story of the infamous Sack of Visby in 1361, when evil Danish king Valdemar Atterdag plundered the good townspeople of Visby at the Swedish island of Gotland, an event immortalized by a painting from 1882 by Carl Gustaf Hellqvist. 

The painting is real. I've seen it with my own eyes. There's just one problem, and it's not a small one either. The Sack of Visby...never happened. It's a propaganda lie concocted generations after the supposed event to gloss over the uncomfortable fact that the burghers of Visby surrendered to Valdemar without a fight, after first betraying the people who *did* resist him! 

Dick Harrison has managed to write a 164-page book about this non-event. Perhaps inevitably, its filled with digressions: William of Occam, the Black Death, 19th century art, and medievalist LARP-ing are some of the topics covered. No hard feelings! At the center of attention stands Gotland, an island in the Baltic Sea, which at some unknown date during the Middle Ages became a nominal Swedish dominion. 

Medieval Gotland must have been a peculiar society. The town of Visby was de facto an independent territory, surrounded by defensive walls to protect it against angry peasants in the hinterland. Visby was controlled by Gute and German merchants. The town was officially affiliated with the Hanseatic League, a North German merchant federation dominating Baltic trade. The rest of Gotland was inhabited by peasants, of which the "trade-peasants" (farbönder) were the most prominent. Really a local upper class, they combined agriculture, raising of livestock and long-distance trade. Gute traders were well known, and even criticized by the papacy for selling arms, horses, ships and food to the pagans and Orthodox Christians in the Eastern Baltic region. (As good Catholics, the Gutes were not supposed to sell such items to people potentially at the recieving end of Catholic crusades!) 

While Gotland was thus formally under Swedish suzerainty, the island really functioned as two independent entities, which didn't always see eye to eye: Visby and the rest of Gotland. 

The other center of Harrison's narrative is Valdemar Atterdag, Danish ruler and often seen as the savior or restorer of that nation after a prolonged period when something truly was rotten in the kingdom of Denmark. To make a long story short, Denmark had been effectively divided between Sweden and Holstein in the early 14th century. Valdemar, a former protege of German emperor Ludwig of Bavaria, gradually restored it by equal amounts of force and cunning. Harrison reveals that historians are baffled by Valdemar's sudden attack on Gotland, since the island wasn't considered strategically important at the time. Since the Danish king felt threatened by Sweden, he should logically have prioritized an occupation of Öland (an island much closer to the Swedish coast) and prepare to attack Kalmar. For whatever reason, Valdemar chose to make an opportunistic raid on Gotland instead. 

The peasants mobilized massively and tried to stop Valdemar's army at several points on the road to Visby. Each time, the peasant levy was routed by Valdemar's well trained German mercenaries. The main battle was fought just outside Visby's city gates. The peasants had expected the burghers to come to their aid and fight along them. Instead, the gates remained shut, while the Danish army massacred the peasant detachments. When the gruesome battle was over, the Visby merchants surrendered without struggle and let the Danish king and his troops enter the city. 

While Visby had to pay a large tribute to Valdemar and recognize Danish suzerainty over Gotland, there was never an actual sack. Nor did the king threaten to burn down the entire town, unless his demands were met. Instead, it was the defeated peasant population who was systematically plundered by Valdemar's warriors, many civilians killed in the process. After these atrocities, the Danes simply left Gotland, mission accomplished... 

As already mentioned, the story of the Sack of Visby was invented later to cover up the inconvenient fact that the Visby townspeople had betrayed the Gute peasants during the attack on the island. The legend was firmly established during the 17th century (it's actually treated as real history by the poor nerd who wrote English Wikipedia's entry on Valdemar Atterdag). Harrison has great fun pointing out all the errors and anachronisms in Hellqvist's famous painting. The houses look continental German rather than Gotlandian, the mayor's wife has long flowing hair (something only prostitutes had during the Middle Ages) and a Jew suspiciously similar to Isaac of York from "Ivanhoe" can be seen carrying money to the Danish soldiers - actually, no Jews lived in Scandinavia during the 14th century! 

On a more somber note, Harrison ends the book by bemoaning the fact that much of what we think we know about "history" isn't really so, indeed, it might even be the result of conscious falsification. Shortly after "Visby Brandskattning", Harrison became involved in a controversy around a recent historical docu-drama produced by a Swedish TV network, "Drottningarna", along precisely these lines...