This paper argues that the construction of sustainable peace settlements among great powers rests on a self-enforcing international bargain that impedes rapid shifts in the global distribution of military power and a series of stable fiscal bargains within great powers that both generate sufficient revenues to preserve a military deterrent and prevent programs of rapid armaments expansion. It examines how free resources— public property, natural resource wealth, international transfers, and sovereign lending—insulate governments from having to renegotiate the basic fiscal contract with society and can, as a consequence, create the domestic political capacity to sustain arms races and shift regional and global military balances to their advantage. These claims are examined by comparing the origins of World War I and the Cold War. The reexamination of World War I challenges the prevailing historical consensus by arguing that the primary cause of war lies within Russia rather than Germany. A discussion of early stages of the Cold War shows how the Truman and Eisenhower administrations both considered launching preventive war to solve the same fiscal dilemma faced by German leaders in July 1914.