In the mid 14th century, the Black Death ravaged Europe and killed one third of the population. By 1353 it burned itself out but in many areas severely degraded the power of the absolute monarchs. This vacuum empowered the Hanseatic League, a commercial and defensive confederation of merchant cities that dominated trade on the Baltic Sea (“hansa” is Old German for “convoy”).
For decades, in order to maintain power in Denmark, the Danish kings mortgaged Danish land, and in 1356, King Waldemar IV reconquered and reoccupied that Danish land after being depopulated by the Black Death. On the island of Gotland, the merchants of the Free City of Wisby, a member of the Hanseatic League, mocked Waldemar for being dishonest and unable to manage his finances.
So Waldemar invaded.
In July 1361, King Waldemar landed on the west coast of the island of Gotland with 2800 Danish infantry and German mercenaries. Outside the city walls on 27 July, they were met by the 2000 Gutnish yeomen, burghers, and dismounted knights. Both sides were armed and armoured roughly the same: the knights had plates covering the vitals and joints over mail hauberks, and the yeomen and burghers had “Wisby Plate Armor”, which consisted of metal plates sewn into a leather of fabric hauberk. Both sides were armed with swords, hammers and axes with round or long shields, and an eclectic variety of polearms. Neither side had cavalry. And both sides considered bowmen a waste of precious bodies on the long shield line. As expected, there were no real tactics, and Waldemar’s greater numbers carried the day. Once the line broke, individual Gutnish bands fell in upon themselves, and were isolated and overrun. 1800 Gutnish were killed. The Battle of Wisby was the largest longbowless, pre-swiss pike, purely infantry field battle of the Middle Ages.
Despite the objections of his men, Waldemar decided not to sack the town, but extort it. He decreed that the citizens of Wisby had three days to fill three giant beer barrels with gold and silver (or booze and rattan), or he would massacre them and raze the city. The rich citizens paid Ransom of Wisby within a day, and Waldemar went home.
Waldemar won the first round against the Hanseatic League, but none of the subsequent ones, as the Battle, and more importantly the Ransom, united the loosely organized Baltic merchants against him.