Costs of Major U.S. Wars
http://www.fas.org/sgp/crs/natsec/RS22926.pdf
Provides estimates of the costs of major U.S. wars from the American Revolution through current conflicts in Afghanistan and Iraq. Cost estimates provided both in current and adjusted constant dollars. Costs are limited to military operations and not veterans benefits, cost of borrowing etc. From the Congressional Research Service, posted by the Federation of American Scientists.
