Influence diagrams were first used in 1973 as a way to model political conflicts in the Persian Gulf and measure the value of information collected by the Defense Intelligence Agency. The number of scenarios for events in the region was too large to be represented as a conventional decision tree model. Influence diagrams were initially conceived as a way to create smaller, coalesced decision trees that required fewer probability assessments. However we found that they also facilitated communication between analysts, experts, and policy makers. Influence diagrams later became the basis for new ways of solving decision models.