This study examines various attempts to define the concept of the offensive/defensive balance of military technology, to trace the theoretical consequences of an offensive or defensive advantage, and to measure or classify the balance for the last eight centuries. It is concluded that the last two tasks are flawed because of the ambiguity of the concept of the offensive/defensive balance. There are multiple definitions and multiple hypotheses, but these are not interchangeable, particularly between the pre-nuclear and nuclear eras, where the concept means something fundamentally different. Hypotheses appropriate for one definition may be implausible or tautological for another. It is concluded that the notion of the offensive/defensive balance is too vague and encompassing to be useful in theoretical or historical analysis, but that some of the individual variables that have been incorporated under this broader concept may themselves be useful. Much more analysis is needed, however, to demonstrate that these concepts have important theoretical consequences.