Purpose This study confirmed the historical significance of the First World War US Combat Strength Training Fitness System for contributing in the ROK military sports development. Methods This research method is literature analysis to be focused by the previous US Army Field Manuals. Results Concretely, The meaning of US Army fitness training was divided into four stages. First, this study confirmed the actual condition of the US Army fitness before First World War. Since 1916, US Army has developed a group physical training program applied the items suitable for the war and has systematically reflected the program in the recruitment training. Second, this study confirmed the process of operating military fitness program during the First World War. US Army physical fitness program provided an effective method to suit soldier fitness for war. Third, this study observed the fitness training changes of US Army after the First World War. At that time, US Army focused on maintaining health and basic physical strength for civilians and reserve forces, but US Army ran parallel with basal physical fitness and combat physical fitness after the Korean War. Fourth, this study compared military strength training between First World War and current US Army. Since First World War, the training of US Army has been developed around doctrine and manuals to be maintained the consistency of the system. In conclusion, US Army physical training system of First World War meant to be provided the basis of current military physical education and physical training. In other words, current fitness training is not dogmatic but has evolved, and it accommodated the basics of soldier physical training course from the past.