An “unnecessary war” is a war in which the combatants engaged without articulation of a clear vision for ending the conflict or as an obvious next step in the development of internal or external policies. An “unnecessary war” is contingent upon eminently avoidable errors. Such wars also tend to generate their own specific kind of historiography stressing “war guilt,” “inevitable forces,” “national character,” “stabs in the back,” and “brilliants plans gone awry.” It is sad but true that three of the most influential wars in European History share these characteristics, and the lecture will explore the way that we have come to understand World War I (1914-18), the First Punic War (264-241 BC) and the Peloponnesian War (431-404 BC). These case studies allow us to see how patterns of memory are shaped as active elements in shaping societal aspirations for the future.