on august 10, sigel's flanking maneuver surprised the confederate army. it allowed the union army an early advantage. the two armies fought fiercely in the fields and hills around wilson's creek. after six hours of fighting and numerous casualties on both sides, the union forces withdrew. siegel's attack had at first proved very successful, but fell apart when he mistook the confederate 3rd louisiana for federal troops and allowed them to get too close without being challenged.