One of the most remarkable recent trends in the field of transitional justice is undoubtedly the rise of ‘truth commissions’. With this trend, history moves centre stage in the ethico-political management of the past. However this turn to history is - I argue - by no means a self-evident virtue. The rise of truth commissions in most cases cannot be explained exclusively by their fact-revealing capacities or the desire to conserve the memories of the past. Neither is the methodology or epistemology of academic historiography of great interest to truth commissions. Why then have so many countries recently turned to history in order to attain national unity and reconciliation? The answer must be sought in history's relation to a specific ‘politics of time’. Transitional justice represents an arena for two conflicting ways of remembering which are driven by contrary temporal features. Truth commissions do not appropriate any kind of remembrance, at random, but turn specifically to history, or what I call ‘modern historical discourse’. This discourse tends to conflict with memory, or, more accurately, with a certain kind of memory which, borrowing from Primo Levi, I call ‘memory of offence’. By drawing from modern historical discourse, I argue, truth commissions aim at the restoration or creation of a modern consciousness of time and of the modernist break between past and present, both of which are threatened by ‘memories of offence’ which claim the ‘persistence’ of the past. The focus on the politics of time allows an insight into a performative dimension of history which exceeds its traditional functions of representing the past, of searching for the truth and of generating meaning. While this performativity can help truth commissions reach ‘closure’, it also has negative effects. In order to explain this I borrow some insights of the historian Mark Phillips and the philosopher Preston King. Throughout the article I use illustrations from the cases of South Africa and Sierra Leone.