The concept of balance of power has occupied a central place in the study of international relations since the emergence of the modern state system. At its core, it refers to a condition of stability in international politics that arises when power is distributed among states in such a way that no single state or coalition is able to dominate or impose its will on the rest. The idea has been both a descriptive reality and a prescriptive principle of diplomacy, shaping the way states conduct their foreign policies and organize their security. Yet the notion is far from uncontested; its meaning, operation, and effectiveness have been debated across theoretical traditions, historical periods, and policy contexts. The origins of the balance of power idea can be traced to the Peace of Westphalia (1648), which established the foundation of the sovereign state system in Europe. The multipolar European state system of the seventeenth and eighteenth centuries required mechanisms to prevent any single power, such as Spain, France, or later Napoleonic France, from overwhelming the rest. The balance of power became a principle of diplomacy by which states would form shifting alliances to counter hegemonic aspirations. British foreign policy is often cited as the clearest example of balance of power diplomacy, with Britain acting as the “balancer” to prevent the dominance of any continental power. For much of the modern era, the balance of power was seen as a natural law of international politics, comparable to equilibrium in physics, in which states automatically adjusted to threats through alliances and armament. From a realist perspective, the balance of power is central to understanding world politics. Classical realists like Hans Morgenthau argued that the struggle for power is the essence of international relations, and that balance of power arrangements are the only means of restraining this struggle short of domination or war. Neorealists such as Kenneth Waltz reformulated this idea by emphasizing the structure of the international system: anarchy compels states to ensure their survival, and balancing behavior—whether through internal efforts such as military buildup or external efforts such as alliances—emerges as a systemic necessity. The expectation is that whenever one state grows disproportionately powerful, others will combine to restore equilibrium. Historical examples include the coalition of European states against Napoleonic France, the Triple Entente balancing against the Triple Alliance before the First World War, and the Cold War alignment of the Western bloc against the Soviet bloc. Yet the balance of power has not always functioned in the predictable way that theory assumes. Critics point to instances of bandwagoning, where weaker states align with the rising