 The site was selected by Captain Hiram Grant earlier that day while Brown was ahead scouting.A group of Dakota soldiers under Zitkahtahhota (Gray Bird), on their way to attack New Ulm, chanced upon the U.S. soldiers camping in a tactically weak position.Hidden by the ravine and the tall prairie grass, the Dakota surrounded the camp and attacked at dawn, inflicting heavy casualties and killing most of the army's horses.