Definition/Scope: The designated subordinate unit whose mission at a given point in time is most critical to overall mission success. It is usually weighted with the preponderance of combat power. FM 3-0(Old version) The friendly unit or group (controlled by a single designated commander) that constitutes the principle means by which to accomplish an objective. The coimmander ensures the success of the main effort by providing it the preponderance of the support and by alerting supporting units to reinforce, or if necessary, assume, the main effort.
Broader Terms:military forces