The Rise and Fall of the Great Powers

Kennedy's central mechanism is 'imperial overstretch': as a great power's relative economic strength grows, it typically takes on expanding global military and strategic commitments, but those commitments tend to keep growing even after the underlying economic base that funds them starts to relatively decline (often because economic growth shifts to rising rival powers). The gap between commitments and resources gets bridged temporarily through debt, tax increases, or currency debasement, all of which further erode the long-term economic base, accelerating decline. Kennedy's history shows this pattern across very different eras and technologies — Habsburg Spain's silver-funded wars, Britain's post-WWII imperial commitments outlasting its industrial dominance — arguing the mechanism is structural, not specific to any one empire's particular mistakes, and applies to any power whose military ambitions outpace the economic growth that has to sustain them.