Current and proposed U.S. Marine Corps doctrine proclaims the many virtues of the Marines as an "expeditionary force in readiness." As America's "911 force," the Marine Corps is tasked to be the military force "most ready when the nation is least ready." A Ground Combat Element (GCE) combined with an organic Aviation Combat Element (ACE) and a Combat Service Support Element (CSSE) provides a potent military force, rapidly deployable anywhere in the world. Capable of operating at the tactical and operational levels of war, the Marine Corps undoubtedly contributes significantly to the total force projection capability of the United States. Operating independently, however, the ability of the Marines to project combat power over time, space and depth may be limited. The nation maintains a requirement for an operationally durable force. Operational durability is the sustainability of an operational force throughout the entire depth and breadth of the theater of operations for an indefinite period of time. Operational durability consists of four elements. These are time, depth and breadth, sustainability, and the moral and material forces of a country. By analyzing the structure, doctrine (current and proposed), and the requirements that the nation has placed on the Marine Corps against operational durability criteria, a determination can be made as to whether or not the Marine Corps is an operationally durable force. This analysis concludes that both in current and proposed doctrine the MEU (SOC) and the MEB are arguably not operationally durable. Under current and proposed doctrine the MEF is operationally durable. The results of this monograph have applicability to the development of the U.S. Army's Interim Brigade Combat Team (IBCT) concept. As a rapidly deploying force, the IBCT presents a formidable, flexible force that is tactically significant. But is the IBCT operationally durable?

ADA 389396 Approved for public release; Distribution is unlimited. The opinions and conclusions expressed herein are those of the student-authors and do not necessarily represent the views of the U.S. Army Command and General Staff College or any other governmental agency. (References to these studies should include the foregoing statement.)