Four years before the outbreak of the First World War, the world famous naval historian and strategist Alfred Thayer Mahan warned of the approaching conflict. In The Interest of America in International Conditions, Mahan recognized that Germany's effort to add a strong navy to its already powerful land army threatened to upset the balance of power that had prevented a major war in Europe since 1815. He understood that American security could be endangered if Germany dominated the European continent. Mahan's geo-historical approach compared Imperial Germany's early twentieth century quest for hegemony to previous attempts by Napoleon's France, Louis XIV's France, and the Austrian and Spanish Hapsburgs to upset the European balance of power. Each previous bid for dominance brought forth a coalition of powers that restored the balance of power. Mahan foresaw in the early twentieth century that a new coalition of powers, including Britain, France, Russia, and the United States, would be needed to prevent German domination of the continent. The Interest of America in International Conditions, however, is more than an analysis of the approaching First World War. Mahan's geopolitical approach focuses on the permanent and enduring features of international relations that affect how nation-states interact on the global stage. Consequently, though written in 1910, Mahan's analysis remains relevant to understanding the geopolitics of the Second World War, the Cold War, and today. This new edition contains a lengthy introduction about Mahan and the significance of his writings on international relations by Francis P. Sempa, who has written on geopolitics.