For some inspiration - here is a link to a good history of the Teutonic Order from founding to Prussian Crusade.
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There is also an excellent review of a similar DBA event online that was held by the WADBAG guys, called the Baltic Crusades.
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The battle inspired a fantastic painting in 1878, by Jan Matejko of Poland. A nice version of it is online, with a fantastic closeup of detail showing Grandmaster Ulrich von Jungingen.
Finally, a nice video of the battle exists in four parts on YouTube (in Polish but with English subtitles).
Part 1 shows the two commanders (Jagiello of Poland and Ulrich Von Jungingen) planning their strategies and making speeches.
Part 2 shows the stratagems talk with the commanders (showing their secret plans - wolftraps vs. hiding in the woods), and the delivery of threats by the German Knights to the Polish command.
Part 3 shows some good action starting with the charge of the light horse (Lithuanians - practically a Mongol Horde, ala Krigbaum) against the German Foot. Pathetic. Then the Teutonic Knights come back at em.
Part 4 ends the battle with some good fight scenes. Knights on foot fighting over the Polish banner...Teutonic Knights charging in wedge. Cool stuff.
Some images of medieval Baltic warriors (poles, lithuanians, etc)
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Anyway the event should be a great time. Come and play.