This is the 5th, revised and updated, edition of Seapower: A Guide for the Twenty-First Century. The sea has always provided the basis for mankind's prosperity and security. With the emergence of an increasingly globalised world trading system in the early part of the 21st century, this became ever more obvious. Contemporary conditions have therefore required navies to adapt and to expand the range of their interests, activities and responsibilities. The Houthi assault on international shipping in the Red Sea and the need to monitor sanctions and ‘dark fleet’ operations shows that these tasks are important and developing fast. Even so, and especially with the re-emergence of potentially de-stabilising great power competition, traditional hard power naval concerns still predominate. This book investigates the consequences of all this for the developing nature, composition and functions of the world's navies, and provides a guide for the changing but crucial role of seapower in the