This study is a historical analysis of how theory becomes strategy. While we know theory relates to strategy somehow, this relationship has not been comprehensively modeled for students and practitioners who must guess about how to win from one context to the next. Guessing in war demands the use of theory for conjecturing about what to do. The role of theory in practicing the art of war is particularly critical since war provides little or no opportunity for hypothesis testing before life and death is upon the strategist, statesman, warrior, and civilian. This analysis looks at strategy development across four theories of action from two different eras - two from World War II and two from the post-Cold War era. One cannot say how much theory determined the outcome of events in each case. However, the peculiar force of theory is always present and follows a general model where four levels of theory combine to provide concepts and logic that guide strategy development in accordance with the changing character of war. Each level entails various propositions and assumptions that combine into an argument about how to win.