Admiral Raoul Castex is France's most important modern naval strategist. Military historian Eugenia Kiesling offers the essence of Castex's original five volume study, Theories Strategiques, in a useful one-volume abridgment and a very readable translation. It emphasizes the admiral's method of strategic analysis while omitting most of the chapters of historical narrative. Included are chapters defining strategy and relating it to policy and geography, analyzing the role of maritime forces and the significance of command at sea, prescribing a theory of conduct of operations, and introducing Castex's favorite themes: strategic manoeuvre, strategie generale, and the theory of "perturbation". Two narrative chapters on German operations in the North Sea from 1914 to 1916 remain as examples of the author's historical style. The introduction places Castex's work in four distinct contexts: the international debate among naval theorists on the nature and importance of "command at sea," the controversy within France between advocates of the "historical" and "material" schools of naval strategy, the contemporary concern over coordinated naval strategy for total war, and his contribution to the formulation of French strategy between the world wars. In an era of expanding global responsibilities and shrinking national economies, Castex's balanced view of naval power offers many insights for today's new generation of naval thinkers.