First published in 1943, this book has long been the key resource for U.S. Navy officers preparing for command at sea. This sixth edition reflects the sweeping changes that have occurred over the past decade in the mechanics of how command at sea is executed and the context in which commanding officers work. Among these changes are the adoption of a new maritime strategy that identifies maritime security and humanitarian assistance as core competencies, a post 9/11 environment in which maritime intercept operations and irregular warfare are key, the rise of piracy, increasing joint and combined operations, the growing capacity to share information, and the modernization of the fleet. An expanded discussion of the submarine-related aspects of command is also included.