The war broke out over the question of who had the right to live at Saukenuk and on adjacent lands. Black Hawk here explains that he and his forefathers felt a natural right to the land they farmed and had lived on for generations. The U.S. government, in contrast, claimed legal right to the land through the stroke of a pen in the Treaty of 1804.
In going to war, the U.S. was asserting its property right in a commodity. The Sauk, on the other hand, were fighting for a sacred space that connected them to their heritage. The government fought largely from political and economic motives. The Sauk and Fox fought largely from emotional and religious ones. Ignorance and misunderstanding about such fundamental cultural differences was one factor that helped produce the war.
For other examples, see the "Treaty Councils" section of Turning Points in Wisconsin History.