The southern Baltic coastline was an amazingly wealthy area at the time due to the huge volume of sea trade. From Wiki:
The defeat of the Teutonic Knights was resounding. According to Teutonic payroll records, only 1,427 men reported back to Marienburg to claim their pay. Of 1,200 men sent from Danzig, only 300 returned. Between 203 and 211 brothers of the Order were killed, out of 270 that participated in battle, including much of the Teutonic leadership.I might have a personal connection, too. My grandmother's family is from Danzig and Marienburg and I've traced them back to the late 1700s. I wonder if any of them were involved in the battle 370 years earlier.
There was also the Hanseatic League, which was a cooperative venture organized by northern German city-states, persisting for about 400 years, ending for all practical purposes due to the Thirty Years' War.
The battle of Grunwald or in German, Tannenburg, was a pivotal moment in the development of the Polish state. It is eulogized even today and made into a grand Slav vs Teutons story, which it wasn’t quite.
It cemented the Lithuanian(which contained most of modern Belarus as well) Polish commonwealth that lasted until 1793.
Your ancestors may very well have been on BOTH sides of the battle!