This chapter examines how geographical setting shapes the conduct of war. It first provides an overview of the ways that physical geography influences the tactical identities of armed forces as well as their strategic effects, focusing on practices that lie at the heart of ‘joint’ warfare—in which land, sea, and air forces cooperate to their collective advantage. The discussion highlights the strategic possibilities presented by warfare in different physical environments—that is, land warfare, naval warfare, and air warfare. The chapter also considers the strengths and weaknesses of forces that fight on land and sea and in the air, unconventional warfare fought on land, the maritime strategy employed by navies, theory vs practice of air power, and coercive bombing. Finally, it analyses the strategic potential of space war, the expansion of war into cyberspace, and the use of ‘cyber’ weapons in information warfare.