Hegemonic War

The concept of hegemonic war is a key element in classical and neoclassical realist analysis of structural change in international relations (IR). Within this realist tradition, hegemonic wars are conceptualized as the means through which changes in the leadership, hierarchy, and structure of the international system take place. A hegemonic war is triggered by a shift in the distribution of power within an international system. This shift may be the result of new political, economic, social, or technological conditions or developments, or even of natural factors, such as natural disasters, that exceed human control. As a result of this shift, the actors who dominate within the international system and are the main beneficiaries of the status quo face a direct challenge from rising actors, who benefit from the new redistribution of power and want to redefine the structure of the system in a way that reflects the new balance of power and their interests. Consequently, hegemonic wars are systemwide wars where what is at stake is the leadership and structure of the international system, as well as the set of principles, values, and rules that are to dominate in a rising new international order. Hegemonic wars are then both the historical vehicle through which change within an international system takes place, and the main determinant for the direction of this change and the nature of the new international order. Robert Gilpin attributes the first use of the concept of hegemonic war to Raymond Aron who, analyzing World War I, argued that in this type of war, hegemony in the state system, even if it is not the conscious motive of the competing actors, is certainly the inevitable outcome of the struggle.

A number of important texts appeared in the second half of the 20th century that used variants of the concept of hegemonic war in their attempt to develop theories for analyzing historical change and continuity within the international system. These include A. F. K. Organski's model of power transition and George Modelski's work on long cycles and global wars. The work of historian Paul Kennedy on the rise and fall of great powers could also be included here. Yet, the most influential and most frequently used source on the theory of hegemonic war is Gilpin's work, especially his book War and Change in World Politics.

According to Gilpin, the theory of hegemonic war founds its origins in Thucydides' analysis of the Peloponnesian War, where, for the first time, the uneven growth of power among states is taken to be the main driving force in the evolution of international relations. Gilpin distinguishes between five stages in Thucydides' analysis of hegemonic war. There is a relatively stable international system characterized by a rather stable hierarchy of states. However, over time the power of a subordinate state begins to grow disproportionately, which leads to a collision between this rising state and the dominant state of that system. The struggle between the dominant and the challenging state for preeminence leads to the formation of systemwide alliances and to the bipolarization of the international system. As a result, the international system becomes increasingly unstable. A new equilibrium will be restored when this disjuncture between the old structure of the system and the new redistribution of power within the system is resolved. In history, in most cases, this new order is the outcome of a hegemonic war, that is, the struggle between the hegemon and its challengers. The main function of a hegemonic war is the reordering of the system in a way that its structure reflects and matches the new distribution of power. Thus, war is the penultimate stage in the theory of hegemonic war, whereas the new equilibrium and order that follows this war is both the final stage in the evolution of a hegemonic cycle and the first stage of the next cycle, which will also follow a course of growth, expansion, and decline.

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