This chapter examines the forms of naval warfare and the roles for naval forces today and into the future. It identifies that navies are likely to continue to be called on to operate within a complex and often contested security environment and that navies and other maritime agencies will fulfil military, diplomatic and constabulary roles, sometimes in cooperation with others and sometimes in competition. The chapter explores the impact of new technology and new techniques in the light of recent conflict and examines the impact of growing Sino–US naval rivalry. The chapter concludes by arguing that naval policy is best understood within a wider maritime context that reflects national priorities, meaning that there is no fixed template that dictates the naval policy of a particular state.

This chapter explores and explains the evolution of naval warfare from the age of sail through to the present day. It examines how tactics and technology have changed over time and discusses the impact this has had on wider maritime strategy. The chapter argues that, despite the very many changes that have occurred in the conduct of naval warfare, key continuities remain and these can best be understood with reference to the ideas and concepts introduced in Chapter 7. A variety of conflicts and engagements are discussed to illustrate the key developments from the Battle of Trafalgar through to the nuclear age.

This chapter surveys almost 170 years of historical practice of and writings on irregular warfare to stress several points. It provides an empirical basis for assessing current and future irregular warfare based on codified doctrine, including best practices and observations. From the American Revolutionary War to the Second World War, several key themes emerge, including the necessity of force, the counterproductive nature of brute force and the value of objective as opposed to subjective assessments of contextual conditions. In doing so, this chapter seeks to deflate some of the influence of ‘presentism’, a bias that suggests recent experiences are unique and indicative of the future of irregular warfare. In stressing historical continuity, it acknowledges continuous elements in irregular warfare while recognising context differences.

Despite debates on the revolutionary impact of such concepts as blitzkrieg, modern land warfare has had a strong evolutionary dynamic. This chapter argues that modern tactics emerged during the First World War as a result of the need to cope with significant increases in firepower. Further, building on theories developed during the inter-war period, the concept of operational art emerged in practice during the Second World War as a means of connecting tactics to strategy. Modern system tactics and operational art remain at the heart of modern land warfare, although the latter, especially in terms of the idea of a distinct operational level of warfare, remains controversial.

This chapter examines the employment of air and space power in the twenty-first century, considering possible future developments in air and space power out until the year 2040. It notes the growing role of commercialisation in the delivery of air and space power and how businesses such as SpaceX have become a part of military operations through contractorisation. The chapter notes how Western air power advantages have been eroded by developments in Chinese aerospace and the proliferation of increasingly sophisticated missile systems. The rise of drone warfare is covered, along with the procurement of a range of drone and missile systems by non-state actors such as Hamas and Hezbollah; the chapter concludes with considerations of the ways in which this presents challenges going forward and a repudiation of the suggestion, presented by commentators such as Van Creveld, that the ’age of air power’ had drawn to a close.

This chapter develops the argument that land, in the form of the ground that warfare is fought on, gives land warfare certain unique characteristics, including its political significance, variability and resistant nature as a medium. These characteristics in turn shape the nature of the forces that fight upon land, making them complex, human-centric and persistent, and giving them the potential for the power of decision. Land warfare is complex: its prosecution requires navigating a wide array of competing trade-offs including those between manoeuvre and attrition, centralisation and decentralisation, and attack and defence. Land power, however, is composed of much more than land warfare, and joint and multi-domain capabilities make a vital contribution.

This chapter examines concepts and theories associated with naval warfare and maritime strategy. It begins with a discussion of the unique nature of the maritime operating environment before exploring the idea that navies have particular attributes or characteristics. It introduces the key principles of classic maritime strategy before exploring alternative approaches often employed by those facing an enemy stronger at sea. Concepts addressed include command of the sea, sea control and denial, fleet-in-being, blockade and guerre de course. These are explored with reference to relevant theories, to contemporary commentators and to current naval doctrine and maritime strategy.

This chapter explores the different forms strategy can take in practice. This involves, in the first instance, looking at offence, defence, deterrence, compellence, offence, and the miscellaneous uses of force. From this conceptual basis, the chapter ends with an examination of strategy in the contemporary setting. This includes a synopsis of the current state of the strategic landscape, identifying the most important trends and challenges extant in strategy. The four areas covered are the Ukraine War, technology (cyber power and unmanned systems/AI), nuclear weapons and strategic ethics.

This chapter surveys modern experiences with irregular warfare from the Second World War until today. Specific attention is paid to the ‘golden age of counterinsurgency’ during the Cold War as well as its more recent ‘renaissance’ and expansion, to include counterterrorism, in Iraq, Afghanistan and globally. The themes here are continuity and change: the former in the shape of relatively unchanging principles based on best practices, and the latter in terms of organisational adaptation, most frequently in the form of specialised units. The chapter identifies and explores four pathologies related to irregular warfare that make countering or conducting it difficult, including mistaking ways for ends, politicisation, over-inflating or mirror-imaging an opponent and the agency of groups too often assumed to be under your control. It concludes by addressing myths associated with specialised forces and irregular warfare and suggests that success results from understanding this form of warfare’s highly political nature.

This concluding chapter notes how changes in the strategic and intellectual environments have been reflected in the three editions of Understanding Modern Warfare. At the same time, it is noted that certain themes and principles have remained constant through all editions. This reflects warfare itself, which is characterised by continuity and change. To illustrate, the chapter identifies eleven constants and five areas of change. It is concluded that the art of war is, at least in part, concerned with finding an equilibrium between these two positions. The practitioner must adapt to change, while still respecting the enduring nature of war.

This chapter outlines the environmental characteristics of air power, particularly the challenges of operating in the air environment. It introduces readers to the way in which modern air operations began during the First World War and the subsequent theorising by a number of key figures who focused upon the strategic aspects of air power and the belief that air power could bring about rapid and decisive victories. These theories are contrasted with the events of the Second World War, which led not to independent air power but the further illustration of the importance of air power as a whole, operating both independently of surface forces and alongside them as a precursor to discussion in Chapter 11.

This chapter argues that the future form of land warfare is far from certain. For some, the future is net-centric warfare, an information and technology-focused view on the changing character of warfare. To meet the demands posed by the changing character of conflict, armies must embrace the theme of multi-domain operations. However, history suggests that in the future multiple forms of land warfare are likely to coexist because the practice of land warfare is shaped by many different political, economic, social and cultural contexts.

This chapter helps readers make sense of the array of activities that can be considered as irregular warfare. As an umbrella term for a particular form of warfare, its methods consist of terrorism, insurgency, revolution, coup d’état and civil war. The chapter compares and contrasts these methods according to the level of resources they employ, their respective centres of gravity, strategic and tactical orientations, mechanism for success and duration. It provides a useful taxonomy for students seeking to better comprehend irregular warfare but narrows down subsequent study to its two most prevalent methods: terrorism and insurgency.