This article examines soldier performance optimisation, enhancement, and augmentation across the three dimensions of physical performance, cognitive performance, and socio-cultural understanding. Optimisation refers to combatants attaining their maximum biological potential. Enhancement refers to combatants achieving a level of performance beyond their biological potential through drugs, surgical procedures, or even gene editing. Augmentation refers to a blending of organic and biomechatronic body parts such as electronic or mechanical implants, prosthetics, and brain–machine interfaces. This article identifies that soldier optimisation is a necessity (...) to protect individual combatants and to give them the ability to make legal and morally justifiable decisions in battle. While enhancement and augmentation of military personnel can lead to accelerated and more destructive warfare, it can also be argued that there is an ethical and moral responsibility to provide combatants the best opportunity for survivability, and that better functioning, less fatigued, and better informed military personnel can make better decisions in battle. There is also a moral responsibility of the state for the combatants themselves, and short-term military success must be balanced against the short- and long-term health and wellbeing of the personnel. This article concludes that it is both the intent and the degree that decide the acceptability. (shrink)