The relationship between the fields of System Dynamics and Operational Research has not always been close and convivial. This is perhaps surprising, considering the strong overlap in ideas that the fields display in their modern form. However, this talk will go back to the roots of the two fields, exploring the parallels in the historical development of both during the Second World War. There will also be a foray back to the Ancient World via the Second Punic War to consider a famous precursor to whom both fields might look for their founding ideas. Finally, a recent development which both confirms and strengthens the links between the two fields will be discussed.