This study examines the significance of friendly fire in U.S. naval surface and submarine operations during World War II and argues that the occurrence of self-inflicted casualties is a function of the frequency and intensity of naval combat. Additionally, the causes and factors contributing to naval fratricide are identified and discussed to naval fratricide are identified and discussed using historical cases. The crucial result of this thesis is that even the most technologically advanced and highly trained force is subject to surprisingly high rates of friendly fire.