The U.S. Army requires a virtual dismounted soldier simulation capability for training, mission rehearsal, and concept development. To meet that need, the Army Research Institute, the Army Simulation, Training, and Instrumentation Command, and the Army Research Laboratory participated in a four-year research and development program to create a demonstration virtual training system for dismounted small-unit leaders. The concept was that repeated practice on realistic scenarios in the simulator, enhanced by training features and after action reviews, would build decision-making and coordination skills. Computer-controlled or semi-automated agents would represent friendly forces, enemy forces, and civilians. The goal was to produce a training system that was realistic and effective, yet required few support personnel to fill the positions of subordinates and role players. Progress was assessed during annual culminating events, series of exercises conducted with Infantry soldiers at the end of each year to obtain objective and subjective data about system capabilities and training effectiveness. This paper describes the results of the fourth and final culminating event, during which three groups of soldiers each participated in a series of eight tactical scenarios in virtual simulators over a two-day period. Ratings of unit performance and responses to questionnaires covering simulator capabilities and training effectiveness were obtained. The paper briefly reviews the key technological capabilities developed, but focuses primarily on the results of the human performance and training effectiveness assessments. Between 82% and 100% of leaders said that their performance improved as a result of the training, depending on the task. Similarly, observer ratings of squad performance on comparable scenarios were slightly higher at the end of training than at the beginning. Trends across the four years are described. Major accomplishments and remaining challenges are discussed.