This report investigates the "low-density battlefield," and the use of armed drones in this environment. A low-density battlefield occurs when modestly-sized ground forces operate over vast geographical areas, without continuous fronts and with vulnerable lines of communication, and can choose when and under what circumstances to engage in battle. The report defines and discusses a generic armed-drone class, based on the real-world Bayraktar TB2, Grey Eagle and Reaper drone types. It constructs four low-density battlefield vignettes in a Nordic-Baltic setting, evaluates the use of armed drones therein, and defines armed drone missions. It outlines and discusses requirements, concepts, capabilities, strengths and weaknesses of armed drones, while providing some final suggestions on future development. The armed drone, as defined herein, has great potential as an effective capability for a number of tasks and missions identified in the low-density battlefield settings, especially in lower conflict levels and in the face of ambiguity. Its main strengths are simplicity, low cost and endurance. Its main weaknesses are firepower and survivability. This immature concept needs to be integrated into current force structures, and there is room for other improvement, but the allure of adding incremental but expensive improvements brings the peril of feature bloat and exploding cost.