In the global security environment of the future, sea basing (loosely speaking, the ability to assemble, equip, and support forces from sea platforms without relying on land bases) will be critical to the Navy and Marine Corps' ability to project-and sustain-forces ashore. With sea basing, Marine combat power can build up more quickly in a littoral area, and the need to move large amounts of supplies ashore will be minimized. As such, sea basing clearly will be useful in the event of joint forcible entry operations (JFEOs). This monograph describes the global environment in which JFEOs might occur and the role of naval power in that environment. It also examines and analyzes various options for substituting naval ships built to commercial standards (so-called black hulls) for those built to military specifications (so-called gray hulls) to achieve cost savings or enhanced performance