A battle commander, in planning and accomplishing a mission for today's battlefield, must consider an infinite number of variables and uncertainties, including a complex combination of individuals, equipment, terrain, and environment. With these myriad decisions by individuals and crews, the need for training in decision making and tactical operation has become critical. However, without prior preparation and an in-depth and timely rehearsal, dealing with this combination of complex variables can lead to disaster. Mission rehearsal is required by all crews to be fully qualified for today's complex battlefield. Rehearsing missions utilizing fielded mission equipment fulfills only a part of the requirement. A full system that could evaluate situational awareness, decision making, team coordination, and employment of units in combat is needed to bridge this gap. With simulation, the environment would represent crucial aspects of the real world by properly preparing the crew and weapon system to complete specific missions. This paper discusses the definition of mission rehearsal, mission training, and mission simulation. It further addresses mission rehearsal from a training standpoint, makes a comparison and a subjective analogy between the mission and mission rehearsal, and proposes a set of requirements necessary to provide simulation systems capable of supporting mission rehearsal.