A panel for field erecting an assault course with the panel supporting a bullet retaining member on at least one face with the panel erectable on a base member and securable to similar or identical panels to form an assault course and a method for field erecting of the assault course comprising the laying of a base member on top of a terrain surface and then erecting a walled enclosure around the perimeter by positioning the panels on top of the base and then securing the panels to each other and to the base member with fasteners to form the assault course.