We conducted a theoretical investigation of a complex command and control (C2) operation—the manoeuvres planning processes in Army land-battle situations, to improve understanding of how technology can best be designed to support planning and course of action development. We drew upon results from cognitive task analyses and interviews with subject matter experts and insights gleaned from observations of Army training exercises and experiments to make inferences on the C2 activities carried out in preparation for tactical manoeuvres. In this paper, we summarize several critical human factors issues associated with planning in a rapidly evolving environment, as identified in our investigation, and describe system design concepts aimed at addressing these challenges to distributed collaborative planning of C2 activities. We conclude with implications for the application of these findings to other C2 domains.