I read about it a excelent book called "Poland" by a famous author, I forget who.
Amazing battle with the Polish and their allies the Lithuanians and Tartars vs. the Tuetonic knights.
One of the key elements in the battle was after the Knights had lined up in battle formation the Polish king refused to engage making his men hide in the woods and let the Knights sit in their battle formations in the hot sun for hours before deciding to attack.