The concepts of incremental cost, opportunity cost, sunk cost, and cost allocation are identified and discussed in the context of early U.S. foreign policy. The case is derived from an authentic exchange of views between Thomas Jefferson and John Adams about how the United States should protect its merchant shipping against the Barbary pirates. Both men compare the cost of waging war against the Barbary States with the cost of paying ransom for captured U.S. seamen and bribes to protect future shipping. Adams quantifies the opportunity cost associated with not taking any action. Jefferson articulates an incremental costing argument, on the assumption that the U.S. should build a navy regardless of U.S. policy toward the Barbary States. The case constitutes a brief introduction to management accounting by illustrating various cost concepts. The case lends itself to a discussion of how cost information can be chosen to support a particular course of action, and it can also prompt a discussion of the historical origins of management accounting.