The Aftermath of a Great Power War

Wars between states are rare, and great power wars conflicts that involve two or more of the most powerful states in the international system are even less common. Still, such wars have historically been among the most consequential international events, as they lead to massive casualties and destruction and have the capacity to reshape societies and the international system. A review of historical great power wars shows that prewar predictions about who would fight, how long the war would last, and how the world would look afterward were often wrong. This history underlines the need for defense planners to carefully examine their assumptions and to seriously consider both intended and unintended outcomes of great power conflicts. As the Department of Defense increasingly focuses on competition with Russia and China, RAND Project AIR FORCE (PAF) examined four scenarios illustrating how hypothetical wars with these countries could produce unwanted consequences for the United States even if the United States is victorious. This report was finalized in January 2021, before the February 2022 Russian invasion of Ukraine. It has not been subsequently updated.